200cc is almost an entirely different game. I see some people here are having some troubles. Some tips I learned from my time playing 200cc (and I think I faired pretty well in the GAF room).
1. Don't always use jumps/do tricks. Control is so important.
2. Choose a kart that's good with handling and turns. Don't choose top speed over handling.
3. With so much speed comes momentum. Sometimes wide turns are the best. I find doing a nice wide turn powerslide in a track like baby park can be better than taking the inside turn (and forcing to break).
4. Breaking is essential during powerslides, especially if you are going to fly off the track. During a powerslide, if you brake, you still keep your boost at the end. So you can brake to nearly a dead stop on a turn, and when you can still boost back to normal speed. It's not ideal, but better than flying off the edge.
5. If you are really going to fly off an edge, just let go of gas. Hitting a wall/flying off an edge is really the biggest thing to avoid.
6. Bullet Bills can be really, really useful now. On a tough set of turns, use it right before you would normally fly off the edge. Works really well in Neo Bowser City and Big Blue. Golden Mushrooms on the other hand....god help your soul. I just use a boost or two if I can, then totally let it run out.
Hope some of this helps.