If you're going to paint again tomorrow, just wrap your brushes or rollers in plastic and set them aside in a cool place. If your painting chores are done, clean your tools thoroughly. Latex washes off tools and trays with warm water. Oil-based paint requires a thinner or mineral spirit. Wear plastic gloves and work the solvent into bristles or nap and rinse until the solvent is clear. Once dry, store brushes hanging bristles down in their original wrap or paper. Rollers should dry and store standing on end.
Consider three-way lamps; they make it easier to keep lighting levels low when brighter light is not necessary.