You have entered a very big subject. There is a whole education to be learned in knapping. There are many different methods, and many different ways to do each method. My suggestion is to keep on watching videos and trying to do what you see in them. When something clicks, and you find you can make it work, keep doing that and improve it and add other methods as you can. Once you get a good method of primary thinning, work at perfecting it. Once you find a method of secondary thinning that works, perfect it. Some knappers, me included, do a lot of pressure flaking, while some use little or none. If you work a lot of flakes or bottle bottoms, you will probably do it mostly with pressure flaking. You will find that you learn this hobby in spurts and over time learn many different techniques and methods.
As for direct percussion and indirect percussion (also known as punching), I prefer to use direct percussion for primary thinning and indirect percussion for secondary thinning. Indirect makes it a lot easier to hit exactly where you want to, not deviating to either side, and not striking too high on the platform. It is also my best way to thin pieces to a very thin width to thickness ration. I can pattern my flakes better with indirect.
With any glass including obsidian, I recommend keeping a glove on the holding hand. There are some cheap nitrile gloves at lumber stores and gardening stores.
Never brush any flakes or slivers of any knapping material from your leg pad with your hand. Use the rock you are chipping as a brush or pick up one end of the leg pad and shake the flakes and slivers off.
As for slivers of glass in the fingers, I usually get a good magnifying glass and find the sliver. Then I use a sharp knife with the blade turned up on edge and drag it across the piece of glass. Most times it will get the thing out. One of the benefits of the magnifying glass is that it lets you know what angle the glass is leaning toward. Knowing that makes it easier to drag the knife the right direction.
Happy chipping.
WA
