Although I have a dehumidifier (two actually) I don't really like to use it. Gives off more heat that what is comfortable for me. My clean room, the room I build in and where all of my wood is stored, is on the small side 8' X 16') so I find that a small room A/C is idea in removing moisture and controlling the temperate I like (70 degrees and 45% RH). In fact the A/C does a better job in lowering the humidity than the humidifier does.
I'm glad the topic came up. Building in a climate controlled environment is probably the most important any single thing you can do. Without it, your wood selection, your bracing patterns, what kind of glue you use, how many routers to buy.........none of that is important if your instruments aren't going to last or will be constantly changing. If you are building for yourself and don't have the resources to build in a CC room, there are some things you can do to help cut your losses. If the humidity is high in your area, these include assembling, gluing up plates and braces, etc during the driest times of the day and never build when it raining outside. When you are finished with a procedure, throw your work in a dry box. This can be a closet, and old refrigerator, a large box, that is constructed or modified with a light bulb, small fan, etc. Keep it warm, not too warm, and keep the air flowing. Eva-Dry is a small closet dehumidifier you can find at Ace Hardware for about $50. It's small, quiet and works pretty well.