I have used 1 inch foam to make my head. It's near impossible to glue everything together and I run out of about 4 hot glue gun sticks in like 30 minutes! >:l I do also have a question. To put the fur on, do I just glue it?
good thing glue sticks are cheap lol. i'm using them like water. All you do is glue it on, just make sure you don't have any opening to large or the fur will sag a bit. The trickiest part of furring your head is to hide the seams. Obviously you can't use one peice of fur, so you must peice peices together. The trick I am using is to fold the very edge of the fur peice to hide the seam, then glueing it right to the edge of the peice that is on my head and making sure that they touch. This hides the seam really well and also you don't get any dried glue bumps anywhere. I'm using short fur for my head, so this helps. If you are using long fur, this might not be necessary, you might be able to hide the seams in the fur. check out matrices.net for some cool tips and ideas, it's what I am using for mine. Check out my two threads about my head all foamed up, and then my furring thread. Mine is about 1/4 furred right now, working on it at the moment waiting for my glue gun to heat up so I can fur the ears the rest of the way and finish the muzzle.
You could also try covering the head in a plastic bag, covering that bag in duct tape, and then tracing out the fur patterns you want. I haven't tried it, but you can cut the fur along the tape, sew it together, and then glue the whole thing on at once.