I found a couple articles doing a basic Search, but this one seems to be the easiest to read as well as incorporates the other ideas.
Disclosure: I have not tried this myself and I have no affiliation with the site linked below.
What you will need
Dry Cleaning solvent
Steps to Clean
Although Stephie's answer about the bed tray (or bed table) is probably the best answer, I also want to suggest a very inexpensive lifehack. If you have plastic trash bags, you can lay one out underneath your food before eating. It is much bigger than paper or butter paper, and liquids will not penetrate it. Also, plastic trash bags are very inexpensive, can ...
Get a sturdy tray with a rim.
I would recommend a model that can be cleaned easily (e.g. plastic) and is rather sturdy, so that it doesn’t warp or bend when it’s lifted up or set on the bed. That will give you basically a “table without legs”, or a solid surface on which you can place lots of different things that are prone to spilling, rolling away or ...