When I first got my pixie cut, the first thing I did was fly to Target and buy the first hair gel I laid eyes on. Luckily, that ended up being Garnier Fructis' Pure Clean Finishing Paste. It was a pretty great introduction for me into the wide world of hair gel, and it's an amazingly multipurpose product for any hair type and length.
It works really well for long hair as well. Whenever I buy a new beauty product, my mom stealing it is inevitable. She tries out everything I buy, and this has been one of her favorites. She has really layered hair that reaches just past her shoulders, and her many layers often get frizzy. She sneaks- or tries to sneak- this out of my room while I'm asleep in the mornings and never fails to wake me up (aren't teenagers meant to sleep in during summer?). It gives definition to her layers, adds pieciness to her bangs, and tames flyaways.
Find Garnier Fructis Style Pure Clean Finishing Paste on Amazon here.