For birdshot, just avoid the cheap promo shells. I use B&P Classic or Winchester AA #7.5 sporting clays loads. On stages with a lot of close clay targets, I'll sometimes use Fiocchi Interceptor spreaders.
For slugs, you'll probably have to do some testing to determine what your gun likes. I've pretty much settled on B&P low-recoil 1oz. slugs, but I've also had good results with Fiocchi Aeros, Federal PB127LRS, and Winchester Rangers.
So, now that you have a shotgun, I guess we can expect to see you at the PNTC 3-Gun matches, right?