One other thing I was told. I've been using my wood-burner for some time now on tombstones so it has quite a build-up of melted foam residue which causes it to not heat up as much. Some people were having trouble controlling the amount of melt with a new, hotter tool. If that's the case with yours try hooking it up to a dimmer switch to better control the amount of heat being put out.
Hey Nick. Thanks! I've got to say I really like your skeleton corpses - totally freaky looking!! And you zombie dog turned out great! Looking forward to seeing your display this year.
For the wood grain you could try using a hot knife tool - practice first on a scrap bit of foam to see how it goes - but you might have more success with a soldering iron or wood burning tool. That's what I used and was able to very lightly draw the tool down the length of the sign from one end to the other to make the wood grain. Vary both the pressure and direction of the grain to make it more realistic. I added the knot holes first and the circular grain surrounding them so it was easier when doing the long grain to go around the knots when you came up on them. Once I had the major grain lines done I used a wire brush to further add the finer grain lines. Go easy with it so you don't destroy your previous work. Everything should be done with a light hand. One other thing to really make your coffin stand out and look more realistic is to make sure and do the end grain on the ends of the boards.
Hope that helps. Let me know if you want me to send you some additional detail pics.