According to Google Webmaster tools, my website's top keywords are posts, forum, topic, etc. because of my forums. However, my website is mainly on the word "link". Is there a way to "separate" my forum's keywords from my main site?
the effect of Keywords density is very minior in factoring the rankings.
I'm not sure why you are using forum, post topic etc as keywords for your forum in the first place. Maybe I missed something here.
I didn't not SEO my forums much. Most of the posts in it are spam. It's a very minor part of my site.
In forums, there's stuff like "Post Reply" or "New Topic" etc everywhere, so it affected my keyword density.
Would a subdomain help?
Ok that raises a whole lot of questions in my mind.
Why would general words/phrases be your keywords in the first place? Surely your keywords for your forum page are based on what your forum/site is about.
Why would anyone want to Google “post reply” or “new topic” to get to your site in the first place?
Your keywords are a reflection of the content of the page they are on and are declared in the meta data tags at the top of your page. These are the keywords you should be looking at the keyword density; the amount of times your keywords appear on your page in proportion to the other words.
I barely use keyword meta tags. Google doesn't use it anyways.
What I meant is the "keyword density" of my forum's body. Of course you would see the words "post", "topic", etc on a forum.