The speakers for my Yamaha YPT-220 are not very good so I have started looking for a small amp to play it through. However I have zero knowledge of amps so I was hoping to get some advice on what to look for. I'll most likely be browsing the local Pawn Shops for a used one so any tips on what names to look for, what problems to watch out for, etc would be appreciated.

Also, I have never used an amplified instrument so what is the sequence for attaching things, turning devices on, and so on in order to avoid making unfortunately loud and painful sounds?