Search engines are getting better and better. And what they want is to become more "human". When using keywords, repetition is necessary as long as you think it looks natural. But when it doesn't look natural to human, it's making your effort useless.
On the early years of search engines, people have found out that the more they mention a keyword on their site, the better it will rank within that keywords. Web owners and web masters then suddenly abuse the strategy making many web pages meaningless to read. Then when search engines introduced "weight", or "density" to words, some also abused it by putting keywords into different style of texts. Any algorithm changes can be abused, but as search engines are getting more closer to human in the way it "thinks" rationally, the once abusive behavior can be kept to a minimum.
But if so, how much keywords do you actually need? How many times should you repeat them, and where should they be? What must you consider when using keywords to make you site rank higher within your category?
Read: Keyword Research and Analysis
Appeal By Research And Search
As search engines mature, they're beginning to see how important a keyword can correlate to different other keywords, and they can better understand the position and placement of keyword within an area of a page, or a paragraph to figure out the main point of the web page.
Keywords stuffing once was used more than often. People have abused it, making many web pages and websites unreadable and meaningless. Despite search engines still do have flaws, they're getting better in patching their weaknesses.
To overcome their strength, you may want to search for their weaknesses a bit longer. But that is not necessarily abusing them.
To appeal better on search engines, you can do more research and searching. For example, when you aim for a specific keyword, you may want to see how it performs live by doing the searches yourself as if you're a visitor trying to get to your own website via search engines.
Google and some other search engines provide tools to help webmasters in finding out which keywords suit them best. It's recommended that you use these tools often to know which keyword can describe your post better, when and how.
Search engines are also getting better in understanding queries. Like for example, they're getting better in term of connecting topics and keywords, as well as synonyms and meanings.
Your primary consideration for SEO to target the keywords you're aiming can be described as below:
See Search Results To Provide More
Using the search result snippet, you can understand whether the result you're trying to aim is informative or useful or not. After doing your research and searches, you'll know whether the information you're about to give can make search engines see you better.
If what you have is useful, and adds to the already existing information the web already has, you can accomplish the strategy by getting into the knowledge itself, crafting the sentences and target the keyword you're aiming.
And when talking about keyword placement, things are getting easier for you. You can put keywords in your domain name, the title of a page, the headline, the content, and repeating them within paragraphs. This is not just to influence search engines, but also to show how informative your content as a whole.
Analyze and Describe
Keyword counts is frequency, and styling of keywords is density, or weight. Before, search engines use the two terms to understand what a page is all about. The algorithm that resembles TFIDF (Term Frequency Times Inverse Document Frequency), looked for those less frequently used terms on a web and see if the website they're crawling have a higher concentration of those terms if compared to other websites.
But as search engines mature, they're not seeing this as a priority anymore. What they prioritize is how the piece of content they're indexing can meet the searchers. that you have and those are the searchers you want to target. To do this, you need to make some keyword matching strategy.
When doing your research and searches, you may want to see other people's web pages to see whether the terms and phrases exist on their site. If you don't see those in them, you can consider in making your post relevant to the keyword.
For example, if the phrase "art" is what you aim, there is already a lot of competition out there that is giving explanation about art as something that about "human activities and the products of those activities involving imaginative or technical skill." But "art" is what you want to describe as something else, like for example your own app/brand name/your name, you can describe it as it is. Search engines' topic modeling can sort and try to figure things out.
All you need is to reassure search engines, and visitors, that "art" on your website is not the "art" that most people see. Make your post about it by describing it in details. Do some SEO on the page and try to get backlinks. Search engines' topic modelling is going to figure out on its own.
As search engines are learning and updated with better algorithm, they can use their already massive database of queries that people have performed on them, to understand what visitors actually want. Search engines are trying their best to be meet their users' intention, and to do so, they're trying their best to use what they have in experience in order to be better in achieving their goals.
Seek Opinions and Engagements
As more contents are posted on the web every day, people don't want more of them. What they want is something better, something more informative, influential and demanding.
When you have your content posted, you need to know whether visitors would engage with it. Will you content matters to them? Will it able to help you in achieving your goals? Will they click on the links, navigate to more places on your site, engage with the call-to-action button you provided, or will they just leave and never return?
On the web, people keep asking themselves whether a site's page matters to them or not. If they see it appealing, they'll click on it, read what it has to say, and spend their time to satisfy their hunger for information. But if it's not relevant to what they're seeking, your page's existence is just going to add up your bounce rate.
To amplify your post's voice, you need to do much SEO and frequent high-quality writing. Create more backlinks on respectable sites and contribute to communities on the web. If you can make other people remember your "art" as a brand. for example, search engines will consider this.
Search engines store users' usage data. When they monitor what people searches, they can understand what visitors are doing when they arrive to a site. So if someone searches for you by including "art" as your brand, this is a signal to Google and others that they have to rank your your website when people search for "art".
Repeating Your Keywords
So search engines are getting better in knowing what you want, what can you do to make your keywords stand out? Repeating those keywords of yours is like saying to search engines that you're aiming for those words. When too many is bad, how many is good?
To understand this, you must first know what your page is all about. How do you write the sentences in each paragraph, and how each paragraph shows its meaning. When you know specifically what your page is all about, that is your primary keyword target. You can at least mention one of the keyword on your page's title element.
You can then add the keyword on the headline of the post. Then you can put some a little density to it by stylizing it. Then you can add one in the page's meta description.
Putting more on other places on the page, like for example the sidebar or the footer can increase its frequency without annoying people or search engines. As long as you think the placement, the density, and the frequency looks natural to you, your effort is considered well done.
Natural repetition will make human and search engine visitors see the consistency, without annoying them. For human, it's getting into their psychological perspective, while on search engines, it's not seeing it as keyword stuffing or spamming.
There is no golden rule in describing the number of repetition you need for your keyword. It all depends on the way your write, the way you want to be informative, and the say you want people to understand what you want to say. Count the number of words you have on your page to get to know the repetition of words you have, and make your targeted keyword repeated a bit more.
If your website have images, you can also consider in doing a bit of image optimization using alt attribute. For the image, it should correspond to what your image attribute is saying. Your image can perform better if its file name also correspond to its HTML attribute.
Getting all those to perform together flawlessly could make your content, and its images, to get a good amount of traffic. Whether its from a click-through-rate or people citing it, you're getting better in targeting long-tail keyword on search engines.
Then comes the page's URL. This is not critical, but can be necessary if you want to be specific. Having the URL to include the keyword you're targeting can be an influence to search engines, and humans, to understand what your page is all about, even before they click on it.
And if you have subheaders on your site to describe different attributes of the post, you may as well put your keywords there.
Playing with Synonyms and Words
Another way to describe your keyword without annoying visitors is by using synonyms. Some web owners and webmasters see an increase in visitors when they're exploiting synonyms into their strategy. Synonyms are managed automatically by Google and other search engines, and there are a few ways to ensure that you can have an increase of visitors and ranking, just by not overdoing it.
Using the Keyword Planner for example, you can see the similarities of a word you came up with. The increase in traffic can be small, but can also be significant. It's all up to your niche and your own research and strategy.
Google has made efforts in making its algorithm more "human" by using Hummingbird update. With it, the search engines has moved beyond word matching to match intention and understanding. Synonyms is just a way to describe your strategy, the concept is to make your keyword appeal to humans in a way that repetition is to create consistency, making people understand what you're trying to say without annoying them.
By playing with keywords and their synonyms, you can get a wider glimpse of your audience's intention in order to make them visit your site. The drawback in this strategy is that Google is also stemming words that have similar meaning, and also plays with them, just like you do.
With Google stemming words, unnecessary repetition is becoming even more unnecessary. The more you use a word, the more Google will stem the word. Despite it may not annoy people to the very least, it can trigger Google in saying that you're stuffing keywords. When using synonyms for your keyword phase, you need to take caution. And again do some researches and searches.
Conclusion
What search engines want to do is to know more about humans in order to serve them better. On the web where information are almost limitless, people don't want more of them. Instead, they're seeking for better information, the things that they don't find elsewhere.
Using keywords is just a way in many ways in signaling search engines for them to record what, how, and where they should rank you. On the web where information is abundance, being different is becoming more necessary because this can appeal people without them expecting.