For the best results, it's important to pay close attention to the preparatory work. The wall must be clean and smooth when you start plastering. You also need to be careful to smooth out the putty to avoid edges. These three steps will help you succeed.
Make sure to remove nails, screws, unevenness and wallpaper residue.
If the entire wall surface is uneven, you will need to plaster.
Have plastic cover, paint and tools in place.