In general, it’s not great idea to use water on your painted wood, so dust frequently to keep from having to deep clean more than necessary. (But, as long as you don’t use water too often and dry it very well, your wood will be fine.)
When it’s time to do a deep cleaning, start by mixing a tablespoon of mild liquid dish detergent with about a gallon of warm water. (Even if you don’t think you’ll need this much cleaning solution, that’s the amount of water it takes to get the detergent adequately diluted.) Get a sponge damp (not soaking) in the soapy water. Scrub the dirtiest parts of the wood first. Then, rinse the sponge out in the soapy water and simply wipe the rest of the wood down.
Dump your soapy water out of the bucket, and fill it with clean water. Get your sponge damp again with this water, and wipe the wood down to remove the soapy residue.
Don’t forget to rub the wood with a towel to dry it off, making sure you get into every little crevice. Don’t let it air dry since that can create water spots.
If you find can’t get into a small little crevice, try this trick: Tape a little piece of sponge to the end of a pencil. If the area is dirty, put a very small amount of liquid detergent right on it. Then, get your little sponge piece damp in the soapy water and use that to clean the crevice. To dry, use the same technique with a cotton ball or a small piece of rag.
Now learn how to clean your art work.