It always amazes me how martial artists spent so much time developing their biceps, shoulders, and even pectoralis muscles, but completely neglect the most important weapon they possess, their fist. Training the fist should be a part of any martial artists training regiment. No matter how strong your shoulders or core are, if you hit someone with a weak fist, it's like hitting them very hard with a piece of paper. All martial artist should train their fists on a regular basis.
You need the most basic of equipment. You can even start with a folded up towel on the ground.
Always remember to start off very slow and build up to this, just like you wouldn't get on a bench and try to benchpress 500 pounds right away, build up slowly and incrementally.
This video will give you some basic instruction, and if you have anymore questions, feel free to contact me.