So I have only done this since this winter so I can still count myself as beginner but I really think this could help anyone here.
So before I start meditation or invocation I do a special kind of breathing from a man called Wim Hof.
To simplify you take 30 deep breath but only half out.
After that you empty your lungs and hold your breath as long as you can.
You breath in fully and hold breath around 10 seconds and tense your whole body and then do it two more times.
After that you are going to be light headed and tingly and it makes me go in to a deep meditation really fast.
A lot of people get other positive results from this breathing technique also.