How to choose the best keyword?

[The Leader]

Find the website that is number 1 in the market you are in and put its url in the google adwords keyword tool and see which keywords its using and then follow!

[airforce1]

I think for the on-page seo you might want to add your keywords in title tags, meta description tags, h1 tags, page contents, inner pages linking texts. While for off-page seo, you might use your keywords in anchor text of backlinks and social bookmarking titles and tags. Of course, use variants of keywords.

Wish this help,

[battuk]

The easiest way is to trace the opponent.
The best way is to ask lots of people
I usually compare google adwords suggest with yahoo.

[Peter Clarke]

keyword research is not an instant acticity, nor is it something that can be taught in a forum post. I teach an introduction to keyword selection and that alone takes an hour. Teaching the subtlties takes another 2-3 hours.

[jambee]

You can use some of the tools to look for keywords:

https://adwords.google.com/select/KeywordToolExternal
http://www.keyworddiscovery.com/search.html

[icecape67]

keyword spy is actually a really good tool for keyword research as well

[Padalda]

I think it choosing a right keyword depends on your site content itself.

[JennyRipley]

I think the keywords should be related to your websites and exact.

[seowebsitetraffic]

Choose the key which is having high volume

[TerryTurner]

Google currently has a few keyword tools that are accessible.
In their Adwords system, they have a Keyword tool and a "traffic estimator sandbox". They furthermore have a "search-based keyword tool" that you'll desire to visit.