Yiorgos,
When I first started PRing, I did really well, because Steele's voice on the back of tape 1 relaxed me really well (then I finally started using that paraliminal tape). Then I stopped doing very well, because I was trying to relax on my own, and I wasn't really getting it.
I'm starting to get it now, so it's very possible that it maybe the actual PRing process that's hindering you.
Do you have the book or the home study course?
-Ramon