Flint knapping is a primitive skill that can be very satisfying. It requires some basic tools for the beginner to be able to tap into the fun. Some of these can be taken from natural materials and some can be made from purchased material. It just depends on how authentic that you want to be in your flint knapping.
A leather apron or a hide to lay across the legs while knapping are advisable. Eye protection such as safety glasses are also needed. When knapping, sharp flakes can fly off and cause damage if you are not protected. You will also need some leather pads that can be used to hold the pieces that you are knapping.
When you start with a big piece of suitable obsidian, quartz or other type of material, you will need a hammer-stone to break away flakes that can be fashioned into hatchets, spear points, arrow points or other cutting tools. The hammer-stone should be a dense, smooth stone that will hold up when breaking the knapping material. The blow from the hammer-stone must be strategically directed toward an area of the stone to be knapped to followed natural "grain" of the stone and fracture it into long, thin pieces suitable for knapping. Some pieces may be suitable for cutting or scraping just as they come from the "mother" stone. Others will need knapping to reach a usable shape.
Once the flakes are removed with the hammer-stone, they can be worked with billets or pressure flakers. Billets are small clubs fashioned from wood or antler. By striking the edges of the piece to be knapped strategically with the billet, removal of small flakes is accomplished and the shape of the desired point begins to take shape. Controlled force is required not to try to remove too much at once. Being overly aggressive can damage a piece beyond use. If a large piece is damaged, it can often be salvaged by fashioning a smaller tool from it.
After rough shaping with a billet, pressure flakers can be used to reach the final shape desired. Pressure flakers may be made from small antler points or can be stiff copper wire inserted into wooden handles. Antler and copper are both softer than the stone being knapped, so It "hangs" the edges of the stone as pressure is applied and breaks off flakes to shape the item. To get the final sharpness on a spear or arrow point, copper wire with sharp ends can remove tiny flakes to impart an incredibly sharp edge. Obsidian flakes can have surgically precise edges and are super sharp.
This is only a basic introduction into flint knapping and tools required. As you progress, you will refine your techniques and open up an interesting world of primitive art and tool-making.