Step 1: Planning makes perfect
Before we get any farther let me clear up one common misconception.
VIKING HELMETS DID NOT HAVE HORNS
Horns were not on viking helmets, horns would have gotten in the way. imagine this, every time you bring your sword over your head you knock off your helmet, sounds like a good idea to get rid of this problem doesn't it. Horned helmets came from Opera not history.