The best way to take good care of your Ragamuffin Co. clothing is to wash it inside out.
These should be only washed with like colors. You can certainly machine wash the garments in warm water that is around 104°F/40°C. Keep in mind that you should only use non-chlorine bleach if necessary and do not iron the decorated (printed) areas. Tumble-dry these garments on medium.
If you are worried about your clothes shrinking, wash as you normally would, but hang/air dry instead of using a dryer.