A set of wolf jaw tongs are a must have, beyond that, its a matter of preference, how you forge and what kind of stock you forge from.
A flatter is also a must in my book. Hammer is a preference thing, but there are some arguenents to be made for which styles are most efficient. You'll probably be best to find a style of cross peen that you like, but will eventually evolve to something else if you get serious about moving metal efficiently.
A tomahawk drift is a tool that replicates a shape that should occur naturally from the way tomahawks were/are traditionally forged. Smiths didn't historically drift hawk eyes with a teardrop shaped drift, forging the cutting edge distorted the punched/drifted hole to that shape. Whether or not that matters to you is a personal question, but I would encourage you if you're interested in cultivating proper technique, to learn how to correctly punch and drift.
Interacting with accomplished blacksmiths is one of the best ways to learn how to forge correctly, and you can learn basic thought proccesses that'll keep you from having to unlearn a lot of bad habits later from just "winging it". Beat enough bar stock and you'll eventually learn how to forge knives, but it will encourage a linear attitude toward forging methodologies that will hold you back from ever really knowing how to masterfully manipulate hot steel.
I know this, because I've experienced it. Having spent time with some "serious" smiths, I realize how much better off I would be, if someone had shown me the right way to do things in the first place.
That may not matter at all to you though, many knifemakers I think prefer to figure out their own way to do things, and are less concerned with how they get there, than the end result. That's a perfectly valid approach, and produces some of the best work out there. Personally, the process is more interesting to me than the end result.
Brian Brazael told me that he loves forging because it's a thinking man's game. I never thought about it that way before, but watching him work is like watching a Chessmaster play. Most of us are just out there beating steel into submission, but each blow from his hammer is part of a multi step plan that sets up the transformation of the base stock to its final form, in an evolution that's far from linear or obvious. That is, until you think about it, and learn the language of moving metal.
