This principle is important enough to warrant bold text:
When optimising your website, you should base your decisions primarily on what’s best for your visitors.
There are 2 very compelling reasons to follow this advice:
1) Search engines today are rather cleverly built, so that they look for pages that are going to benefit users. It’s unlikely you’ll find a ‘trick’ that fools many search engines into thinking your site’s more useful or important than it really is. Any attempts to do this are likely to end up with you being penalised or even removed from the listings (there are both automated and manual checks in place for this sort of thing). A good example would the once popular technique of writing hidden text repeating keywords to make your page more popular. It won’t help.
2) Users will only return to your website or recommend it to others if it’s useful. If the content is written in such a way that it tries to cram in lots of keywords, but doesn’t read well or efficiently deliver relevant information to users, you’re not going to get any repeat business.
There are many techniques outlined in this website that will improve your popularity with search engines and don’t necessarily enhance the user experience, but none contradict this key principle and you should always keep it in the forefront of your mind. What’s good for users is good for search engines.