Summarize this article:

Air Mattresses, like regular mattresses, come in twin, full, queen, and king sizes. It’s probably best to splurge and get the full or the queen. Even if you only plan on having one person sleep on it, the twin is still quite small and may not offer enough room to spread out comfortably.  Make sure to buy one that has an electric air pump. Many come with this built right into the mattress. Blowing up an air mattress yourself is arduous and time consuming. More expensive doesn’t always mean better when it comes to an air mattress. Much of the comfort will come from how you set it up, so don’t feel like you need to spend an arm and a leg. A decent full sized air mattress can be purchased for anywhere from $45 to $75 dollars. Unless your air mattress has a headboard, you’ll want to be sure there is a wall behind it. This will act in place of a headboard and keep your pillows from falling back behind the bed in the night.  You can also put the mattress up against some furniture like a couch or a regular bed. Keep the mattress away from drafty windows. Don’t place it too close to a radiator. Not only will this make you too warm at night, too much heat runs the risk of damaging the plastic of the air mattress. Most air mattresses have vinyl or plastic underneath to keep them from moving. This can make squeaking noises at night and isn't always the most effective at keeping the mattress in place. Put your mattress on carpet if you can. You can also put a blanket or yoga mat under the mattress to help keep it silent and stationary. Unzip a sleeping bag and place it on the mattress. This will act as a cushion to make the bed softer. It will also help you keep warm as the plastic of some air mattresses can become cool at night. Cover it with a fitted sheet to keep it in place. You should treat an air mattress like any other bed when making it up for the night. Start by putting a fitted sheet on it. Then lay out a regular sheet and and a blanket. You can tuck them under the mattress to help them stay put. Finish it off with a warm comforter and some pillows.

Summary:
Choose which size to buy. Set the mattress up against a wall. Place the air mattress on a soft surface. Use sleeping bags. Make the bed as you would a regular bed.