Find a place on the floor where you can connect yourself to something fixed, for example the tubes of the heating system, or the hinge of a door. Do not connect yourself to a cupbourd or wardrobe. Things may fall out of it when you struggle. You can connect yourself either by your ankles, or with a chain around your neck. Otherwise you may start crawling around and looking for your toolbox. I would hate it if you freed yourself too early. It is a good idea to put tools for freeing yourself on the floor, but they should be far out of your reach as long as you are connected.
I always use a blanket, twice folded, with a sheet on it. I recommend that you do not lie down directly on the carpet. Even carpet that appears soft, can graze your skin severely, when you struggle. Also if the keys fall out of your reach, the blanket can help you to get them within your reach.
Make sure that the keys will fall near your hands, but not on you, and that you will be able to reach them.