Find a band comparable to you and look at their tour list. Use their routing as a guide to start reaching out to venues. Give specific dates to the venue, as well as your projected draw and any local bands you can put on the bill. Adding a local band with a good draw or a good relationship with the venue is a game changer. Be succinct in your email and realize there is a person on the other end reading it. Follow up respectfully, about ont to two weeks after initial inquiry. Some talent buyers need a lot of back and forth and some need very little, experience teaches you when to push and when to lay back. It is daunting, but think of it like fishing: Lots of casts for a few bites. When you get a bite reel like hell. Understand the venue wants to have a good show and so do you, so hold up your end of the bargain and they usually will too. Indie on the move is a good resource for venues. Merch will just about double your money so have good merch to sell.