How to smooth rough walls - what's the best method?

Most rough walls result from old wallpaper, peeling paint, or just poor-quality plaster. Depending on how rough the surface is, you'll need different approaches.

For slightly rough walls, sanding with sandpaper (grit 120-180) usually does the trick, followed by several thin coats of spackling compound. You apply the compound with a wide putty knife, let it dry, and sand it down again. Repeat several times until the bumps disappear. It takes a while, but it's the most reliable method. Finish with a finer grit (240) and you'll have a smooth surface ready to paint.

For very rough walls or if you want to save time, self-leveling spackling compound is worth it - you just spread it and it evens itself out, saving you multiple rounds. The important thing is to dust everything thoroughly beforehand and prime the surface, otherwise nothing sticks properly. Some people go for special surface coatings or textured wall smoothers, but honestly that's usually more expensive and not better than classic spackling. With patience and the right materials, you can get any wall smooth.