In the words of a beloved children's character, "take chances, get messy, have FUN!"
Whenever MJ and I paint it's almost always in the afternoon. It's important that we start off well rested (i.e. less likely for meltdowns, better listening ears, etc.) It is also important that I keep my expectations low. It is probable that things will get very messy- that's why we have soap and laundry machines. It's probable that her canvas will extend to her body- that's why bubble baths are so much fun. It's probable things will not go how I plan them- that's why deep breaths and realistic expectations are so helpful. :)
In addition to the right expectations, setting ourselves up for success also includes the environment and our tools. I l-o-v-e IKEA's roll of paper. (We use it all the time for lots of different things.) For painting, I roll out a large piece and use masking tape, or in this instance painter's tape was more accessible, to tape the paper down to the floor. Ideally, you want to be somewhere where clean up is relatively easy if paint splashes or the "canvas" accidentally extends away from the paper. We like to paint on paper on the kitchen floor. The paper is also a good visual boundary for your little one to paint within. You will also want to use washable paints. We love the WASHABLE dot-a-dot markers. But sometimes I get brave and use acrylic paints, but I always mix the paints with 1-part paint and 2-parts dish liquid. Acrylics aren't washable if they set in so the dish liquid extends the amount of time you have before it sets in and it helps release any that has started to set in. No matter which you use, it is important to remember to have or help your little wash her/his hands promptly after finishing their masterpiece. This will control paint from traveling throughout your house and it's important that the don't ingest it either. :)
When you start to create together try to relax and just have fun. If you're anxious something will get ruined try to remove it. You can always scoot nice furniture away and painting is just as fun in a diaper as it is in sweet play clothes! When painting play time is over, promptly wash you little's hands and toss any painted on clothes straight into a washer or soaking tub. No need to stress- you probably had some other laundry to do too, right? :)
I hope this encourages your heart and maybe inspires you to get creative with your littles. I try to remind myself that one day I'm really going to miss the messes from creative play time.