Wood
Lightly sand any rough spots. Fill rough spots and holes with wood filler and then sand. Wipe with a damp sponge. If you want a stained background, use a water-soluble, alcohol-based wood stain. You may need to seal the wood.
You can apply your cutout directly onto untreated wood, but its better to apply a sealer. Before sanding wood paint a base coat first as the water-based paint lifts the fibers of wood way from the surface so when you sand the paint the fibers are easily removed. The first coat of paint highlights imperfections that you can correct with filler.
When using a wood base, remember that oil and water dont mix. The most common decoupage glazes are water-based and wont adhere properly to wood that has been stained with an oil-based stain.
If youve stained wood with an oil-based stain, you need to seal it with an oil-based sealer. If you want to decoupage a piece of old furniture and arent sure of the finish, find an inconspicuous spot to test your glaze.
Glass
Wash your glass item with soap and water, rinse thoroughly, and wipe dry. Wipe the surface with rubbing alcohol or vinegar and allow to dry before working on...