I could spend days trying to come up with something on my own but never be quite as happy as I am with this pattern for a Lael Viking Helmet by Mamachee. Some things are worth paying for.
It worked up really quickly and I found the directions to be clear and simple to follow. If you had an uninterrupted 2 hours you would probably have it done.
What do you think? Pictured is the toddler size on a rather large baby with an 80th percentile head. Some vikings have large noggins.