now that you have $150+...move up to the 10NL tables...you have 15 buy-ins. that should be enough, if you are simply "nut camping."
when you go over $300, start taking shots at 25NL.
remember, if you hit variance (or start playing stooopid), move back down. my number would be 25 buy-ins for the LOWER LEVEL.
example.
you have $300. you shoot at 25 NL, you lose your shirt. down to $240...drop to the 10's until you go above $300 again.
you give yourself one hellofacushion that way.