What keywords should I use?

[Yasoo]

don`t use it for few specific reasons...

This has no impact from the SEO point of view and search engine is not getting or collecting any information from this...so why write more?

If the Meta Keyword tag is smartly inserted then it can be dangerous and this is because you are seriously helping your competitors to see what keywords are you targeting on the page and then he can alter his strategies accordingly to outrank you in search engine from the desired key phrases.

Matt Cutts says "It's possible that Google could use this information in the future, but it's unlikely. Google has ignored the keywords meta tag for years and currently we see no need to change that policy."

However, there are other search engines and directories that use the keyword meta tag. For example, Yahoo! still uses it.

You can use any keywords you need but don`t use meta keywords tag.