There are two common ways to apply shellac. The first way is using a brush and the second is wiping (padding) on the shellac. To brush shellac, use a fine, natural or china bristle brush. You must apply generously with long, smooth strokes. It dries very quickly so you must be careful to avoid drips or blotchy areas when applying. If you noticed you have missed a spot or there are drips, let the coat completely dry before attempting a repair. It is ideal to buff each coat with super fine steel wool to look for imperfections in the finish.
To pad on the finish use a clean piece of non linking medium weight cotton muslin. It is ideal to lay down a smooth, even application in a single long, even stroke. You may need a bit of lubricant for a smooth movement. In that case use a very small amount of mineral oil. When applying work in somewhat irregular patterns rather than just with the grain. This will insure thorough coverage. This method works best on flat surfaces.
One option to consider is combining the two methods together, as padding and brushing work well together. Apply the shellac with a brush and immediately smooth it out with a cloth.
After the shellac dries, lightly sand it with a 400 or 800 grit sandpaper. Even super fine steel wool will suffice. Just make sure to wipe off any white residue then apply the second coat. Repeat until the desired number of coats have been applied.
Shellac produces a high gloss finish, but if less glossy results are desired. Try buffing out final coat with super fine steel wool and applying (non-solvent based) paste wax.