I don't know too much about technique. This only describes the basics, fixing errors requires a good eye and attention to detail.
The key to good, consistent technique is:
- Learn what good technique feels like
- A coach is very useful here. You can also record yourself, or ask friends to look for certain things.
- Learn how to replicate that feeling
- This is mostly you. A coach can only help so much here.
- Hundreds of repetitions at moderate weights, focusing on replicating the feeling.