Cory,
Are you talking about forging your own heads or just hafting and finishing premade hawks? I have made both, hawks and rifles. If it were me, and guns is what I wanted to learn, I would jump right in and learn by doing. Also go slow and ask A LOT of questions here...great guys here that love to teach and help out. As far as forging hawks, obviously it takes a forge and the associated tools. Forging is an art in itself that takes time and practice. Unless you plan on forging your own buttplates and triggerguards, not a lot will carry over to the gunmaking side of things and you will be spending time learning forging when you want to be making guns.
As far as tools, very sharp chisels, rasps and files are a must. Also a good setup for holding your work pieces. Pouring pewter isn’t that difficult. Get you some hardwood and practice inletting if you are hesitant about messing up a stock blank. Just have fun! And remember.....
We don’t make mistakes, just happy little accidents. —-Bob Ross