I also suffer from sea sickness occasionally, and car sickness if I can't look out a window. I've only had one nauseous incident in VR with simracing and that's because I looked in a weird direction.
My tips:
- Don't look in weird directions (ie: don't try to peer over the edge of the cockpit to look at the side of you car) while moving. Keep looking forward or briefly to the sides for some spacial awareness
- Stop as soon as you start to feel sick. Do not power through it. I've heard of some guys being sick for a couple days afterwards when trying to push it. Even further to the point, always look in the direction you are traveling/want to be traveling, unless you're quickly checking for cars around you. Had a friend who was doing fine, then looked to the side as the car started to oversteer and he was done for the night.
- It's a tolerance, you'll build up if you need to.
- Don't look to the sides when stopping the car or when launching. It's pretty disorienting sometimes.
- Make sure you've got a decent framerate. I've found, personally, that I'm fine if the FPS dips into the 30s on occasion (usually sitting at 45 in ASW) but a lot of people can't handle it if it's less than 90 FPS. If you don't have a good PC, don't bother. VR is very resource intensive.
VR is amazing, I can't go back.