1) Being a smoother pedaler starts with a proper saddle height. In short, if your saddle is too high or too short you may bounce.
2) There will be a certain resonance frequency that will cause bouncing...even in trained riders.
3) Shorter cranks help. On 170mm cranks, I bounce around 120RPM, but I'm smooth before and after that. On 165mm cranks, I'm smooth all the way up to 225rpm.
On the road, you don't want to let your bike/cranks get going too fast and get away from you. Stay in control. Use a brake.