Start with JSB dome shaped pellets. 90% of the time these will be the most accurate pellets in the majority of today's pcps. My Cricket rifle shoots both the 15.89g and the 18.13 super accurately. So accurately in fact that I don't think I've ever bothered to try any other pellets.
Also I've had no issues with my Cricket, it has performed flawlessly since I bought it used about a year ago.