My situation: lots of girls in the "friend zone" and not too many new girls trickling in

I've heard that there are ways to stroke a girl's jealousy, and she'll start taking more interest in you. Your thoughts?

Sex up her sister.
Of course, then you'll be dealing with two jealous sisters.
This isn't the most ideal situation.

One good method is to show interests in another girl. meet someone through a female friend(make sure girl is cuter than friend, or close enough)