Before pouring paint in your roller tray, consider lining it with aluminum foil or a plastic liner.
You can throw those materials away after the paint job is complete and reduce the amount of clean up time necessary. Also, try to avoid using the side of a paint brush when covering the corners of your room. You can increase the life span of your flat paint brushes and make the job cleaner by sticking to the flat side – brushing in downward strokes from the corner. If two colors are meeting in that corner, you can use masking tape on the dry surfaces to avoid splatters or bleed over. Once the other surface is dry, you can switch the tape to the other side and complete the job.
If dirt or other debris gets inside the paint can while you are painting an exterior, there is no need to despair. You can cut some spare wire screen (from a screen door or window is best as it is cheaply available at your local home supply store) and place it on the top of the paint. It will not immediately sink. However, as you continue painting and the level lowers, the screen will continue to drop and take the debris with it. Once it gets to the bottom, you can simply throw the can away – but you still will have saved a great deal of paint from the garbage can.