What is the safest way to jelq? how do you avoid those nerves that supply the penis with it's most important quality, and what is the safest way to stretch?

If the nerves themselves do not expand with the tissue of the penis are they harmed somehow by the enlargement? This part doesn't make sense to me, if they are connected in certain areas and then the tissue expands even very gradually, will the nerves expand as well?

I caused some severe damage in my first attempt at this stuff, but I'm going to try again in a few months, and I want to know the safest way to do these exercises please..