In the summer of 2010 I worked at the YMCA of the Rockies in Granby, Colorado. They had THE most amazing craft shop there and I spent every free moment down there that I could. One of my favorite things to do there (among tie dye, mosaics, leather working, ceramics, and beading) was wood burning.
You use a little pyrography tool with different tips and burn your heart away. Well...wood, not your heart. You get my point. I was SO excited to find the exact same wood burner at an art store in West Seattle for super cheap (you can get them at Walmart for ten bucks, too). I went to town this Christmas and made a plaque for everyone in my family. Of course I gave them all away before I took pictures of them, except for Sean's, which is the one I'm showing you today.
I printed off the cross image from the interwebs and typed up the words on my computer and printed them out. Then I did the age old "reverse rub" thing where you rub the back of the paper with a pencil and then trace over the image onto the wood.
The biggest challenge I have with wood burning is the size of the grain and the hardness of the wood. If the grain is too defined it can cause the tip to bounce and it creates kind of a bleeding effect. Also, if the wood is a hardwood you need a pyrography tool with an adjustable temperature (which I don't have, so I just choose soft woods.)
It takes a lot of patience but it is so fun! I finally branched out enough to do a free hand mountain landscape for my dad, which was a lot more rewarding than just tracing someone else's image.