Place drop cloths over exposed floors and furniture. Tape off areas not to be painted. Remove switch plates and socket covers and put them in a bag with the screws so you don't lose them.
Shake up your paint cans. Use flat paint for the walls and semigloss for trim and doors, as it is easier to clean. Start with the flat paint.
Pour some paint in the cup for use with the brush and cut in the room with the angled brush. Start at the wall and ceiling joint and go around the room, using the ladder or step stool, then do the corners and along the baseboards. The cutting-in covers the areas the roller won't reach.
Fill the roller tray one-third full. Slip the roller sleeve onto the handle; load it up in the tray by rolling into the paint and evenly covering the surface. Roll on the paint evenly, taking on one section at a time. Do the ceiling first if you are painting the ceiling. Using the extension pole will save you a lot of energy.
Check the walls after the first coat once the paint has dried, a minimum of one hour. Apply a second coat if you see the old color underneath or spotty coverage. Small spots can be painted with a dab from the brush. Remove any tape from the trim.
Paint your trim and doors once the walls are dry. Use the 2-inch brush. Brush on the doors using vertical strokes. Paint the trim in slow, easy strokes. Don't overload the brush. Semigloss paint has less pigment; you may need two coats. Apply, if necessary, a second coat after the first dries.
Take up drop cloths and tape, and replace switch plates and socket covers. Clean up with soap and water.