If you are looking to change a room's appearance, an easy way to do that is a fresh coat of paint. When you are buying the paint one gallon will cover about 400 square feet. Multiply the length times height to get the square footage for each wall and add them up. For the trim, multiply the length (in feet) by .5 for the width. Make sure you plan ahead as painting a room could take several days. You will also need to plan on working from top to bottom, so if you are painting the ceiling, you'll want to start there. Now that you are ready to go, you'll want to follow these steps:
Step 1: put the brush about 1/3 of the way into the paint and be careful not to scrape it against the sides,
Step 2: paint with smooth strokes feathering out the edges to prevent runs, holding the brush the same way you would a pencil,
Step 3: cut in along the ceiling line first then switch to a roller, and for walls cut in one wall at a time then use the roller.
Rolling the Paint on the Ceiling/Walls
Step 1: Dampen the roller with a wet rag to help the paint stay on, then dip a little part into the paint and roll it out onto the grid or liner to even it out, don't submerge the whole roller, it will make a mess,
Step 2: Roll the paint in a zig-zag fashion starting a few inches from the edge and work in four-foot sections from top to bottom. Go slow to avoid paint splatters and reload roller often,
Step 3: turn the brush on the side to get close to baseboards and ceiling,
Step 4: to remove buildup and runs, press very lightly rolling over the paint from the ceiling to the floor,
Step 5: Apply two coats and do one wall at a time,
Step 6: If taking a break, cover the paint with lids or plastic wrap and cover brushes with plastic wrap or aluminum foil.
Painting the Trim
Step 1: After the walls are dry line the edges with painters tape applying pressure from a putty knife to keep it sealed along the wall,
Step 2: paint the trim with a brush,
Step 3: remove the painter's tape when you are finished painting, not when the paint is completely dry.