There are numerous ways to apply the skip trowel technique with each giving its own stylistic advantages. But the basic concept is the same.
The wall or ceiling should already be taped. Thin the joint compound considerably, yet sufficiently dense to retain its shape.
The first step is to get the material on the walls or ceiling. If this is a ceiling, take a 10″ trowel (which may also be done with a taping knife) and spread it onto the surface (or by spray) to about 1/8″ thickness. With a turn of the wrist, angle the blade and ‘skip’ off from the surface. Perform the motions from random angles and directions. You will want to let the intitial texture set and then revisit the surface to knock off any drooping.
A variant of technique blends silica sand with the mud, for a grainier texture effect.
Broader and smaller blades seem attuned to room dimensions, and this will depend on the situation. They can help scale a texture that is busy, overwhelming, or fitting.
Taping knives are an alternative to the trowel, but these can take their toll on the wrist and these techniques utilize wrist intensive movements.
Note: for walls, the skip trowel is closely related to stucco techniques and modifications toward it can provide a creative appeal.
Other Ceiling Texture Topics