Fortunately I have never even come close to boaking my guts up in a plane but understand that if one does begin to feel like they are gonna gip then to focus on the horizon (guess the artificial horizon will have to do if in IFR!), open up them fresh air inlets, try to avoid heavy meals prior to flying and try not to get hung up over it. Everyone I know who got sick to start with got over it after about 10 hours so don't worry captain.
Good luck,
VFE.