I would take a look at a gay sex book if you haven't already, and check out the different positions if he is also inexperienced. For starters, 69 is always a good bet. For anal, if you are topping, a pillow under his butt and his legs over your shoulders will give you good aim at the prostate, and you can play with the sphincter muscles very easily and tease him. Rimming is a nice way to loosen him up too, or playing with first one, then two, and then maybe three fingers (but clip and file your nails well first, so you don't hurt the skin).
If you are both into each other and excited, almost anything is going to feel good. Especially if you can both communicate to each other with your bodies and movements or sounds, and with words. He will teach you what positions feel best for him if you listen.
Everything ledroit said is spot on. One thing I would add is that if either of you think you are using too much lube you probably haven't used quite enough. Trust me on this, spit is not enough lubrication for first time anal.
Have fun, be safe, and . . . oh yeah, it's time to change your percentages. You are no longer 100% straight dude. :biggrin1: