I believe my friend in Arizona is at quilt camp this week -- but she also took the coloring class. She and several of her group plus friends and class makers did a full sampler project. I'm not sure what the teacher recommends but I'm sure they all did it that way. I'll have to put in a call and probably wait a few days for a reply.
I am sometimes doing techniques and will usually do a few tests for things like color fastness. I'd take a test block, put it in a lingerie bag (or inside a pillow case you don't care about), and wash it with your regular laundry (include a color catcher) and see how the test block comes out. Check for size/shrinkage/ravelling as well as color fastness.
Sometimes I go on to do horrible things to my tests, like boil them, either on top of the stove or in the microwave. Generally I feel pretty secure that the technique or product is safe to use if it passes 1-2 tests.