To begin with, soft lighting and calming music are an important part of setting the mood for a good, sensual massage. The use of massage oil (with a light scent if possible) seems to amplify the effectiveness of a massage. If you've ever had a professional massage, try to remember the process, the hand movements, and which parts of the body are best done first and last (pros tend to start with the shoulders, do the back, the legs, then the arms and the hands). Bigger muscle groups, that take more muscle to massage, are best done first, with softer touch toward the end. The most important part of a massage is to get lots of feedback about what feels good and what doesn't. You can alter the force of your massage, the tempo, all that, based on the feedback. As a dude, let me say this is a wonderful, thoughtful act of generosity, and it's hard to go too far wrong! One last thought: Make it fun. If it's fun for you, it'll be fun for him.