I usually make most of mine about 1" wide x 2-2 1/2" long and around 150 grains when I can. The Cahokia side-notched style is a good hunting design. It's hard to make exactly matched sets, but you can put heavier points on lighter shafts and lighter points on heavier shafts. I like any material that's tough and will get really sharp. My favorites when I can get them are good rhyolite, Kentucky hornstone, Texas flint, and Fort Payne chert. Lots of other rock will work, though. Obsidian gets really sharp, but is weaker than chert or rhyolite. It's still plenty strong enough to cut its way completely through a deer, though.