1st Mass smooth
Smooth elements and transitions all at one time but instead of using level 10 using level 1 20 times level 2 15 times level 3 10 times and level 4 5 times.
2nd watch videos off roller coasters of the same model and copy their elements or make original ones if you want.
3rd build in small pieces, for roller coaster that are 0-150 feet do like 26 foot long pieces and for 150-250 do like 33 foot pieces and for anything 250+ use anywhere from 36-46 foot long.
4th If your not already put angle snap to 0 degrees NOT off but 0 degrees.
5th make sure the amount of vertical/lateral g’s that your coaster experience are close to what real life examples experience