Prepare the wall:
Sand/scrap the walls thoroughly and remove all the dust, grease, and paint.
As you clean the surface, you will find several cracks, holes, and dents on the wall. Fillers are used to repairing them perfectly.
Depending on the manufacturers’ instructions, prepare the filler. Wear gloves before applying the filler.
Fill the holes and cracks by hand to get a smooth finish. You may use a trowel or a flat tool to get a perfectly smooth finish. Let it dry out before painting.