For microfiber towels, never mix them with any cotton towels when you laundry them, the cotton will clog up the materials. Also, use hot water to wash and low heat or hang dry.
The hot water is needed to help the fibers release any materials caught in the fiberrs, but the dryer gets much hotter and can melt the fibers as well, so when drying either low heat or hang dry.
I rarely will use the same towel again for polish or waxing, even after it was laundry. I sort my towels in different grades. Essentially brand new for polishing, like new for interior and drying, kinda rougher for cleaning the engine bay/door sills, and old/rough for mopping up dirty oil during an oil change or cleaning up grime. After that they get thrown away.