This is probably my favorite technique.
Take a wad of tissues (I've found that five is the best number because it's enough to absorb all the ejaculate but not too much to be overly bulky). I would also suggest that you find a brand or style that's really soft to prevent chafing. I don't use any lubricant with this technique.
Lay the tissues on top of each other and then put the tip of the penis in the center of the top sheet. Wrap the whole wad of tissues around your penis, like a parachute. Next, take a portion of the top sheet of your bed and wrap it around the wad of tissues once or twice. Again, it's nice if your sheets are soft.
After this, you can lay face down on the bed and position a pillow between your belly and your penis. So what you've created is a little hole (comprised of the wad of tissues and the sheet) sandwiched between the mattress and the pillow. You can then stimulate yourself by moving in and out of this hole. You could also try it without the pillow, but I like the extra support.
If you wish, you can prop your elbows up and check out a magazine. It's nice having both hands free to flip pages.
For variety, I like to put a second pillow lengthwise under my chest to simulate the feel of a female body underneath me. I can even caress her 'back' with my free hands. If you are a bit tired, you can put the second pillow under your head.
Clean-up is super easy. You just throw away the wad of tissue. If you are going to flush them, I would suggest separating the individual sheets first, so you don't clog the toilet. Usually I just throw them in the trash can.
I also recommend removing the tissues soon after orgasm, or they may stick to your penis. If this happens, don't worry. Simply remove as much tissue as you can, and then soak the stuck part very thoroughly with warm water. It will then peel off quite painlessly.