How choose keywords

Dont need to worry or try to hard in finding a good keyword its really easy but you need to give me more info in what you are building your site about is it to get a physical product commission is it ebook commission is it for adsense. but here I will give you a good way to look for keyword that helps me find a physical product EXAMPLE: playstation 3 it might be over crowded with promoters but its an example make a product review about the ps 3 then move on to another keyword related to the ps3 like playstation 3 move then write about the playstation 3 move product and so on make a website about 5-10 pages google loves content the more content and unique content your website has google will love all you have to do is backlink.
Good Luck

Have you tried using google adwords keyword tools? google it.. its a very good tools for choosing keywords

You'll want to think about who is your target audience, and what the primary focus of your website will be. Need help on this one? Read my article titled Understanding Your Audience.

Jot down a list of words and phrases that you think people might type into search engines when looking for your site. Don't worry about being perfect: just be creative. This might be a good time to review how to brainstorm for keywords and phrases.

Each page on your site should have one to three related keyword phrases that are site-specific. For example,say you have a page all about coffee mugs. Good phrases to target on this page would be coffee mugs, ceramic coffee mugs, or unique coffee mugs. See what I mean? They're all related, and they're all pointing at the same general content on the page.

Your keywords should be used throughout your site copy - where they make sense - as well as in your title tag and various meta tags. Don't go nuts and start inserting keywords every other word, because this is considered bad form. Read more about the title tag, meta tags, and unethical search engine optimization.

It takes a while to get the hang of finding the right keywords that work, but once you've mastered this skill, you'll really see how this can benefit your site. Want more information? Read my article titled Including Keywords In Your Site Content and Source Code.

The best keywords are 2- to 4-word phrases that accurately describe what you offer using everyday language that searchers are likely to type in, and which aren't so competitive that you have no chance of getting on the front page.

Choosing your keywords means choosing what type of people you want to advertise with your product.

Here are some tips in choosing:

*Avoid Single-Word Terms
*Avoid terms that are too broad
*Avoid terms that are too specific
*Avoid terms that are unpopular
*Avoid highly competitive terms