Multi-choice problem: Continue writing the next sentence in this paragraph:

How to mix plaster
Prepare the wall for plastering.
Before you get started, make sure the wall you're finishing has already been, and any seams have been touched up with a base coat. That way, all you'll have to worry about is spreading the plaster, which will require your full attention.

Pick your answer from:
-Plaster is best applied to wood or metal lath, or bare walls stripped of paint and wallpaper. If the wall has semi-gloss or gloss paint on it, you should prime it before adding plaster.
-If you don't have plaster plaster at home, you can order it or buy it in a pre-mixed form and weld it down. You can already have a base coat applied, and you could add it before you move on to the next step.
-Before you start mixing, work out what wall you want to put plaster on. Here are some things to notice when deciding what, if any, parts of your wall you want to use : Surface layout.
-For the best results, prep the walls the same way you might for a painting. Get a contractor to wet down your walls.
Plaster is best applied to wood or metal lath, or bare walls stripped of paint and wallpaper. If the wall has semi-gloss or gloss paint on it, you should prime it before adding plaster.