Now that I know all about keywords & PPC, what to do with the information?

1.) As a small advertiser is it smart to stay away from where the larger companies have the most keywords or best to try to compete w/ them on a low budget?
or
2.) Do is it advisable use keywords not used as much? or are consumers not searching for those words and where the overused keywords are is where advertisers get their ROI?
3.) If a keyword is advertised a lot on one search engine do i go to another search engine to advertise that keyword?

See original post by miss20042005