Best thing to do is to get yourself a pellet sampler pack, straightshooters.com has a good one. Once you find the best performing pellet you're all set to go.
If you are going to use the gun for hunting or pest elimination I would suggest trying some JSB Predator pellets. They are a little pricey but they are one of the most accurate pellets in many of my rifles. They are also devastating on small game. Pyramydair.com has them.
Another pellet I would try, especially for shooting starlings and other pest birds, would be the GAMO Tomahawk pellets. They are a great buy, 750 in a tin for around $5 bucks. These pellets also shoot extremely accurately in almost all my rifles.
RWS Superdomes are usually a good pellet to try at first also, they seem to work well for quite a lot of people in their rifles. But like I said, you can't go wrong getting a good sampler pack.
Jeff