What are the necessary tools I should buy/have beside my first gun?

I am going to buy/build an AR-15 and also buy a Glock 19 or 17. I am wondering what tools, like special wrenches or oil, etc., I should buy to be able to assemble or maintain my guns?

P.S. If I also purchase a shotgun, are there any specific tools I should buy only for shotguns?