1. Wood pieces that you want to paint and antique so it looks like the paint is worn off. You will start by lightly sanding the entire piece and clean it with TSP (degreaser). Take a wax candle and rub around areas that you want the wood to show once you sand off the paint. Prime entire piece including over the wax. Paint in the desired colour and paint product, I prefer Benjamin Moore Aura Satin (Latex), Para Cabinet and Furniture Malemine Paint (Latex) or if you like oil use Benjamin Moore's Collections Oil Satin. If it is a piece that you use regularly, you can add a clear coat overtop. I personally like Old Masters Satin Polyurethane.
2. Furniture pieces that you want to paint and antique and see another colour paint underneath. Start off by sanding and degreasing the piece (TSP). Next, prime with a good primer (Benjamin Moore's Fresh Start is good and can convert old oil paint to latex if you are wanting to use a latex paint). Put two coats of the base colour on first, this will be the colour you see when you sand off the top colour on the edges and around the normally worn surfaces. Next, take the wax candle and rub on edges etc. where you want to see the first colour. Next, paint the piece with the top colour, suggested two coats to get the best finish. Next take sand paper, fine or course or even a sanding block, and sand off the top colour where the wax is. You can put an additional top coat overtop if you desire extra protection.
Here is a list of items I like to have when doing this type of project:
Sand Paper or Sanding Block
Benjamin Moore's Fresh Start Primer
Benjamin Moore's Aura Satin or
Para's Cabinet and Furniture Malemine or
Benjamin Moore's Collection Oil Satin
Any wax candle
Old Masters Satin Polyurethane (if you want a top coat)
Good paint brush
Mohair roller and cage (gives an amazing finish)