Depends what you want, however, theres a billion ways to do it.
If you carry alot of speed, theres 2 main options I like to think of:
High, tight andslow
Low, wide and fast
High, tight and slow means a hill thats tall enough to kill speed, but, is tight enough at the top to produce good airtime and careen the train over the edge.
The Low, wide and fast is the opposite. Itll be alot lower to the ground but carry a very wide radius. Usually this produces longer but less strong airtime. However, if properly designed, both designs can produce the exact same airtime, it just requires very careful math and/or hand tweaking to get the right shape.
It all depends on your land space really. In a tight fix? go with the high one. Takes less space. Got room? Go with the low one. Both too will offer the same airtime, but itll feel totally different. One will be a plastering to the seat with fast speeds, the other will give a quicker plaster but youll get that over the top feeling and of course, a larger change in speed as you slow down more and speed up from falling.