I need a help about on-page seo because I want to do on-page seo my buyer site. Can anybody tell me the full on-page seo tips?
I understand what you are really looking for, but I have a question though. If that site is from your buyer, is he or she targeting you to do on-page for the main website? Or just the inner pages? I think there are many on-page SEO tips you can find in the internet, you just need to learn and implement it. You can Google " Effective On-Page SEO Tips" and from there you can find results. Hope this helps you.
Yes, what bogart said. Also, try those "free online SEO checkers". Run your URL through them. They will tell you a LOT about your site. Example http://seositecheckup.com/, http://www.seorobotics.org/, http://www.seowebpageanalyzer.com/
You should read "Search Engine Optimization Starter Guide" by Google. You will get a clear idea about what's important part of On Page SEO and in what's the exact way to do that.
There are plenty of resources for On-page SEO: https://moz.com/learn/seo/on-page-factors http://backlinko.com/on-page-seo