I assume the shop checked it over and made sure everything is tight, the forks are on the right way round (we've all seen it) and all the other new bike fettling bits.
Your brakes probably just need bedding in, as you know this I assume you know how to do it (and I'm assuming they're disc brakes).
Other than that, get out and ride it, then you'll know what needs fettling. If its saddle/bars/stem then change one thing at a time 'til you know what works.
If you can't get out and just want to fettle, and the bike is brand new, de-grease the chain then re-lube properly, otherwise it'll attract dirt like a, well, like a greasy, sticky thing that attracts dirt.
Enjoy, new bike time is great.