Allright, I have been into (underground) metal music well for more than a decade now, attending countless shows and few festivals regularly every year, and recently the idea has been popping up in my mind, whether I could bring some bands I like to the town.
Despite the fact that I already feel almost like an old fart as far as going to the concerts goes, I have to admit that my knowledge about organizing
a show is very limited, and thats why I would like to ask.
Lets clarify this:
-I have a small shows in mind, 30-150 people, obviously not bigger bands
-I know the perfect club for this kind of concerts in the neighbourhood, where I have seen bands like Attic, In The Woods, Them, etc.
-I dont mind covering some costs out of my own pocket without expecting any returns, as long as it is not too much. I am living in a rich country, but I have s shitty job.

Please if someone can describe the whole process, preferably in detail, and obviously I am especially curious about the financial aspects (who pays what - travel costs, accomodation, renting of the club, sound engineer, etc.) and potential biggest difficulties.

it's all very relative...

some bands are happy to play just for travelling expenses, sometimes not even that if they are touring anyway and going through your town. they'll be happy to sleep on your floor, or that of the venue.

you can have some venues for free as well, if you can guarantee a minimum attendance (they'll make their cut from drinks).

plenty of bands travel with their own sound engineer (who knows their songs, etc.). some venues might insist on their in-house engineer instead (as another one "might damage their equipment"), and then you'll have to negotiate with both parties.

there are no standards. you have to try and make everything work, keep the venue happy (so they take another booking), try to give some of your (hopefully) earnings to the band, even if it wasn't in the deal, etc.

the most usual c**k-up is the backline, the venue may not provide one on the night, even though they say they would, and the band(s) show up without amp cabinets, etc. or the support band, who initially agreed to share theirs suddenly want to leave early. so have a plan B (and C and D) for that.

you start at contacting the bands you want to book, be honest about doing this first time (this may backfire on you, but I'd say stick with it), and ask what their reqs are. if they ask for too much, politely decline and start with someone easier, and you can go back to them for like your 5th gig when you know the ropes...

this is in no way exhaustive or all-inclusive, just some pointers I could think of.

you can try contacting another underground promoter, some are really nice people. others will see you as competition and will intentionally try to eff you up or discourage you. so don't take everything at face value...

start small, with local bands you're on friendly terms with, to see how it pans out, then move to bigger and better things...

and if you want to book my band, our rider is only £2000, 4 bottles of tatra tea and a bowl of m&m's with the brown ones removed

ps./edit: axully, if you're "living in a rich country" (where presumably everyone does everything by the book), start at the venue. they might tell you they cannot deal with you as an individual, so you have to start a company for tax and invoicing purposes. starting and keeping a company running might cost money, even if you're not making any... there are ways round that, usually (legal ones), and in most countries, but that's too long to go into here...