You have a 15000 chip starting stack with the first level being 25/50. This means you have 300 big blinds to begin with. Therefore you should be playing tight in the opening stages, only playing premium hands and low pocket pairs when you're in position and have the correct odds
to call. During this stage you don't want to be getting into big confrontations when you have a marginal holding. I would try and play straightforward and then loosen up when the antes kick in stealing the blinds where possible. Hope this helps and good luck. Tell us how you do.