Different rooms such as bathrooms, kitchens, bedrooms and dining room have slightly different requirements, but basic step-by-step instructions are the same for all rooms. For purposes of clarity, I will be laying out step-by-step instructions for painting a living room. Look at my advice about preparing a room to paint and when you've removed some furniture and placed the remaining furniture in small groups, you're ready for step-by-step instructions to paint a room.
Step 1 - Tape the Room
Apply masking tape at the bottom of the baseboards and under of any baseboard heaters. Use standard beige or brown masking tape on carpets, NOT the blue painter’s tape. And buy the most expensive tape, the cheaper type splits and is very hard to apply. On carpet, the blue painter's tape will come loose. You can use the blue tape on hardwood or tile floors. Make sure that you remove the masking tape within two days, otherwise it will split and be very hard to remove.
Step 2 - Lay Drop Cloths
Once the tape is in place, put down the drop cloths. Cover the furniture with the thicker plastic ones. Cheap thin plastic drop cloths are difficult to unfold, and they split easily. Vinyl butyl or canvas drop cloths are best for the floors, but they are expensive and mainly used by professional painters like me. You may want to buy some of these, they fold easily and can be stored away, but if you don't want to spend the money, get in the habit of saving old shower curtains and plastic table cloths. You can use plastic drop cloths, they are cheap, but have a tendency to move around. Do NOT use newspapers as drop cloths. Paint stores sell drop cloths that have a paper side and a plastic side. These are really quite good. Place them paper side up. The paper will absorb paint splatters, and the plastic keeps the paint from reaching the floor.
Step 3 - Identify the Existing Paint
Before you buy your paint, determine whether the existing paint is oil base or latex. Often the baseboards, wooden windows and other trim are oil based. You cannot apply latex paint over oil base paint, or oil base paint over latex based paint. It will peel and come off in strips. It is simple to determine what type of paint you have. Put some denatured alcohol on a clean rag and rub the surface of the paint. If some paint wipes off onto the rag, it is latex base. If not, it is oil base. The only way to change paint base is to first coat all the trim with an oil based primer/sealer. Then you can apply whichever base you wish. Oil base primer/sealer is extremely volatile, and requires an approved respirator. Good ventilation is not enough, you need to wear the respirator. They are not cheap, but you may be able to pick one up at the paint or hardware store for around $20. A paper dust mask will not suffice, you will get sick from the fumes.
Step 4 - Pick Your Color
I have a good suggestion for choosing your paint color. Use the sample color strip charts you can get at the paint store until you have made a choice, then buy a pint of paint mixed in that shade and apply several foot square areas with that paint in different areas of the room. You may see a difference between the samples on the wall and the little color strips. If you are purchasing new furniture or carpets, take that into consideration when choosing your color.
Step 5 - Spackle and Caulk
Patch all holes and cracks with spackle or joint compound. There are also “lite” spackle products which dry faster. Use a 6-inch spackle knife to apply the spackle, and a 2-inch putty knife to load the spackle on the larger spackle knife. Spackle shrinks as it dries, so you have to spackle lightly, then sand and spackle and sand again. Fabric tape should be placed over cracks so that the crack has less of a chance to eventually crack. Use a very light coat over the fabric tape to “set” the tape. Sand lightly, and put a heavier coat of spackle over the tape, and smooth it out by running the blade at a 90 degree angle to smooth the spackle. Fans can be used for faster drying, as well as heat guns or hair dryers. Clean any dust of surfaces to be painted and along baseboards. Use a caulk gun and caulk around all baseboards, windows and door jambs. Caulking makes for a really beautiful job.
Step 6 - Paint
Laying paint is the last and easiest step. Now that you are ready to paint the room, here are a few tips you won’t find anywhere else. Most room painting instructional articles say to start first by “cutting in” around windows, baseboards and ceiling lines with a 3-inch width of paint. This is wasteful of both time and paint. First, roll the room completely, then whatever the roller does not cover, “cut in” or brush the paint on. You will find that you will only have to cover about ½ inch.
When you roll, don't use the M or W pattern a lot of other articles suggest. For the best results, pros rolls a continuous pattern from floor to ceiling and down again, overlapping each pass by half. This gives you the most even coverage. You will probably need to apply two coats of paint for a good job. Follow the drying instructions on the paint can label, as well as all instructions and safety precautions. Now you have a beautifully painted room.