What You think about it?

Hello guys.. I created a new site, and I wanna rank for 4 different keywords.
I was thinking about tier 1:

a) Create 30 web 2.0 profiles (boosting random keyword)
b) Create 4x20 web 2.0 profiles (20 web's / 1 keyword)

I think b) would be better option, anyway I want to know what You guys thinking about it.

Keywords are relative easy, 7000-10000 searches/month.

PS. About tier 2.. could be good add like 500 articles pointing to every web 2.0 resutl?

Thanks for ideas,
panqnik