Not too bad there. You sure you never tried that before??
Just a few tips on your fire:
Add more highlights or hotter spots toward the front of the box. Make the base of the fire brighter than the tips. So it appears hotter at the front. And watch out for patterns
I agree with Sean, a little more shadowing, and hot spots. Looks good for a first attempt, just keep practicing and try adding a lil more freehand work.