search based on keyword, mass follow everyone in the results, post a few tweets so you have an active account, they will follow you to be nice, unfollow everyone else, rinse, repeat, then just before you hit the people you want to impress unfollow a few more (leaves you with more followers than following, at least temporarily.
At least thats conventional wisdom (and I think you can get a tool to do it actually), I haven't tried it personally so let me know if it works