Creating cool synths is all a question of :
- Expressivity (modulation)
- Clarity (mixing)
- Context (other sounds in track, lead synth?)
The advice I could give you is to stop touching your synth when it is close to what you have in mind.
Depends on the genre but you may also have some expressive synths without being "powerful" (dB speaking);
Sound mixing, effects is really useful but for a start you should prefer creating clean and powerful sounds without any effects (just to train).
FM modulation is a good training.
You could also compare your synths to other synths in banks or even on tracks.
Mid range frequencies usually make the difference (expressivity).
Hope this was helpful,