I just started using wood burning too to make signs.
Step 1: Planning
Take some time to plan out your artwork so it will fit one your piece of wood. I used a scrap piece of wood. I bought a wood burning kit from the hobby show, the letting kit was extra. Lightly draw your design on the wood with a pencil, that way you can easily sand off your pencil lines later. Keep a scrape piece of wood available to set your hot letters on so you don't burn your work space. Use a leather glove and a pliers to take off hot letters without burning yourself.
Step 2: Applying Letters to the Project
I used some strait edge drawing tools to try to keep my letters straight. The tools also helped my avoid drawing extra lines on my project.
Step 3: Finishing Up
Once I finished the artwork, I cut the corners and the top, and added a hook to the back. Sanded the edges and pencil lines. So far I have left it without a finish.