Lay a drop cloth on the floor in the area where you plan to paint. Set two sawhorses, about 5 feet apart, on top of the drop cloth.
Remove the doors from the door frame. Remove the doorknobs with a screwdriver.
Lay one door on top of the sawhorses. Set the other door aside.
Clean the surface of the door with warm soapy water and a clean sponge. Wipe down the door with a clean cloth. Flip the door over and clean the opposite side of the door.
Remove any chipped paint by gently running a paint scraper over the chipped areas. Use a trowel to fill any holes or dents with spackling paste. Allow the spackling paste to dry for four to five hours. Sand the surface of the door with fine-grit sandpaper to create a smooth, even surface. Wipe down the door with a clean, damp cloth. Flip the door over and repeat the preparation process on the other side.
Dip a 3- to 4-inch handheld paintbrush into latex paint. Starting at the top of the door, apply the paint in smooth, even strokes and work your way down until the entire surface of the door is painted. Allow the paint to dry for 12 hours. Apply another coat of paint if needed, and allow the door to dry for 12 hours. Flip the door over and paint the opposite side in the same manner.