How to control the pressure when molding?

Can you give some tips to control pressure on the molding process?

One of the basic rules of scientific injection molding is among the most frequently broken: aim for 95% to 99% filled parts at transfer before packing. (adding pressure)

Thanks for your valuable comments.

First you must find where the pressure you are trying to control is coming from. Nozzle, sprue, Hot runner if you have one, gates and so on.