How to Cut Smoothly?

So far, so good. I cut two basic muzzle pieces out of 1-inch foam and glued them together.

Fine shaping is a problem right now, because almost every time I snip off a piece of foam, I end up taking off more than what I intended, or it just is jagged and uneven.

Here are some photos of the head base and muzzle:

1. Balaclava head base, eye mock-ups added



2. Muzzle side


3. Muzzle front


4. Muzzle back


5. Concept art of finished head


Obviously, I need to build up the sides, even them out, round the entire muzzle, and hollow it out. I just am hesitant to do so, because of the problems stated above.

Any tips or advice would be greatly appreciated.