Concentrate at maximum 2-3 keywords for a page. Based on ranking weight you need to follow the below process in order to get maximum SEO benefits.
1. Add your first keyword in beginning of your title tag and use the other keywords based on ranking weight of that keyword
2. Add your first keyword in <h1> tag in your content
3. Add other keywords in <h2> or other header tags as you wish or based on your page design
4. Avoid too much linking in your contents (at maximum 100 words per link)
Good luck for your SEO success! See you in my next tip.