Welcome to DV

regarding your questions, I find MILD is best to start. And other DILD methods.
WBTB is very good for beginners, naps, it depends. I rarely have/do remembered dreams in naps...so I don't use that.
The success rate is different for everyone, and there is no best technique because techniques work differently for different people.
Try and do WBTB, with whatever, reality checks, dream journals, mantras, etc. When starting out