if you need help in cumming quicker and haven't figured that out by now, then i dunno what to tell you. but putting yourself behind the 8 ball isn't going to help. you'll just stress yourself out. which pretty much defeats the purpose of having a wank. :P
I don't wrap my hand around my shaft.. I just grab it and instead of going all the way around i put my finger tips on the other side.. example I'm left handed so I'll have my palm on the right side and my finger tips on the right side and spread them a little kinda even spacing it feels awesome I don't know if you understand what I mean.