Read your paint can: whatever is recommended as the thinner is probably good for clean-up, too. Brushes are usually pretty easy to clean-up using the appropriate solvent (paint thinner, mineral spirits or whatever). Rollers can be more difficult to clean. One alternative is to drop them into a Zip-lock freezer bag, squeeze all the air out, and throw them in the refrigerator. They'll last for months like that, maybe more...