Iuse water-soluble Jasco paint stripper, an old paintbrush, an old soft toothbrush, and a container of warm, soapy water. I use the paintbrush to paint on the Jasco, let it set for about three or four minutes until it's all bubbly, then dip the model into the container of warm soapy water and scrub gently with the toothbrush. Messier than all get-out, but after about two applications, I've got a nice, shiny brass model that's ready for cleaning, priming and painting.
Jasco comes two ways--water and thinner soluble. I use the water soluble because I have heard that the 'thinner' soluble version CAN attack some of the solder joints. I don't know if this is true or not, but so far, the paint remover has worked very well for me.
Tom