Well, for starters it might be best if you two are in a pretty private area because for me it's easier if I can take his pants off or at least pull them down far enough so I can use my hand a bit easier. Something else that works for me is it might help if both of you are sitting up and having you on his lap. Once again, better access

Oh, make sure you have some lubricant on hand or at least some way to create enough friction and when you start working it with your hand you can add in some kissing too.