Finding a local space that’s completely on board will solve half your problems. Do you have a list of things you’ll need and how much it’ll all cost? Budget it out, make sure you’re thorough, and see if it’s possible for you. There are loads of people who will volunteer to help for free (myself included) so take advantage of that where you can, but budget like you gotta pay for those services.
Think about things like the video guy, photo guy, judges, MC, cashier ect. You’ll probably need to rent a stage, PA and lights too. Some of these things you’ll get for free, others you’ll definitely have to pay for and the prices can rack up. Call some companies who offer these services and get quotes for how much it might cost.
Some of this money can be made back with sponsors and such, but don’t expect all of it. Most companies will provide product (Which you can either sell or raffle off to help bring some money back).
Beyond all that, be prepared to talk about the contest a lot, to as many people as you can. Anything you can do to promote the event and get people through the door.
It’s a lot of work, I’ve barely scratched the surface as I’ve only dreamed of putting on an event, not actually done it. One day I will, but I haven’t yet.