Found this article after a few comic people I follow shared it. I’ve not read it properly yet, but looks worthwhile. I’ve not made my own one yet, but throwing in my own piece of advice, is to network and talk to the local comic community. Sounds obvious, but I’ve seen it happen before.
John Hendrick is very well known on this board as a previous moderator. He knows his onions so any advice should be taken on board.
I suspect what John doesn’t know about comics retailing ain’t worth knowing about. Big Bang is a great shop if you’re ever in the vicinity.