The first step is to try to determine what the stuff is that you want to strip: oil paint, latex paint, varnish, lacquer?.
Then decide if you can work on all the surfaces horizontally, or if you will have to work on some vertically.
Now start reading the labels of all the different strippers on the hardware shelf. Some are general purpose and claim to strip anything at all and you could choose this if you don't really know exactly what you are stripping. Usually a stripper made for a specific material works best.
Then if you can work flat, buy a liquid stripper. Otherwise buy a semi-gel or a gel stripper. These are more expensive, but on vertical surfaces you use far less than with a liquid stripper because it stays put.
The best way to get any stripper to work deeper, and to strip more per bottle, is to cover your work in plastic wrap to hold the solvents in, forcing them into the paint instead of the stripper just drying up.