It sounds weird, but I find the more you fight it and try to hold yourself in your seat, the worse it feels. If you just relax and let your body weight naturally press against the restraints as the force moves you around, you don't really feel much just the force and speed of going fast.
I'll usually go a few years without riding them b/c I'm not near an amusement park, and then the first time I ride one I'll usually be gripping the bar trying to hold myself in place at first. Then after getting that out of my system, I relax and don't grip as tightly, I just have my hand lightly on the bar, and the ride feels so much more tame. You just feel the force of accelerating more than anything else.