Cover all areas you do not wish to be textured. Cover windows, baseboards and door jambs with plastic sheeting and tape it in place.
Add water to your drywall compound until it is a thick soupy consistency.
Apply the drywall compound in small but rough chunks with a trowel, or splatter the wall with compound using a paint brush. Work in sections as you create texture.
Spread each section with a trowel, moving lightly over the compound. Move in different directions with a very light touch so that you leave irregular gaps between the flattened mounds of compound. Let the compound dry.
Cover and tape all areas you do not wish to sculpt.
Apply the drywall compound to the surface and smooth it as flawlessly as possible with a trowel.
Drag a sculpting comb across the smoothed compound. This creates a pattern in the compound. Use this technique for straight or curved lines.
Drape and tape areas where you do not want the compound.
Tape your chosen stencil to the wall or ceiling.
Apply the drywall compound with a trowel across the stencil. Texture the compound by splattering and smoothing, combing or any other method that creates the texture you want.
Remove the stencil from the wall and let the compound dry.