Tongs
Hold it true, or drop it hot.
Hold it, or lose it
Tongs are the difference between forging and chasing hot metal across the floor. They should grip the stock like they grew there, and you'll end up making a pair for every size you work.
What to have
flat for bar and flat stock V-bit for round stock, won't slip wolf-jaw one pair that holds most things pickup light, for small work
Make your own
Buy one pair, then forge the rest. Tongs are the classic first real project — you need them, they teach drawing and riveting, and a bad pair still works better than no pair.