It shouldn't make any difference being uncut,ive never had any problems.
Lube your shaft up with vaseline but don't put to much on,get at least 50% erect,grasp the base with the Ok grip,tighten grip and slowly milk the shaft 2-3 second reps is a good starting point,if you are doing it right the whole shaft and head should get noticably engorged with each rep,doing a quick kegal every few reps helps to get fresh blood into the shaft,by the end of your session your flaccid hang should look bigger than normal,fat and full of blood.
If your not experiancing this then either you are not erect enough or you are not gripping tight enough with the ok grip.