Most venue contracts are five pages of boilerplate wrapped around three numbers that actually matter, and once you can find the three numbers you can sign. They are the door split, the guarantee and the buyout.
The door split is the share of ticket money you keep after the venue takes its cut. Seventy in your favour after costs is common, eighty for a headliner who brings a crowd, sixty in a quieter market, and the word doing all the work in that sentence is costs, so read what the venue has folded into it, usually sound and security and the ticketing fees, sometimes the door staff as well. The guarantee is the minimum they pay you whatever the turnout, a couple of hundred euro for a small support slot, somewhere between six hundred and fifteen hundred for a headliner in a two hundred capacity room on the mainland, more than that depending on how much you draw. The guarantee comes first, and the door split only starts to matter once the ticket money minus costs climbs past it. The buyout is the meal money, fifteen or twenty euro a head or a hot meal at the venue instead, and some contracts hide it, so ask if you cannot see it.
The other four and a half pages come down to a handful of clauses worth your attention. Read the cancellation terms, which usually say that if you pull out inside two weeks the venue keeps the deposit, and if they pull out inside two weeks they owe you a slice of the guarantee. Read the bit about photo and video permissions, and read any exclusivity clause, because the occasional contract will say you cannot play within fifty kilometres of the venue for a month beforehand, and on a tour that matters a great deal. The indemnity language you can mostly skip, unless you have played the room before and seen something that made you nervous.
Sign about a week before the show rather than on the night, send it as a PDF instead of a shared document that can change under you, and keep your own copy. And if a venue will not give you a contract at all, that is not a relaxed venue doing you a favour. That is a venue that is about to get something wrong, and you will be the one paying for it.
Love,
Marten