This all assumes you have a local store that supports the game
1.) Organize a terrain making day prior to the tournament at the sthop
2.) Pick a shop to play at with enough table space
3.) Charge a registration fee and then pay out the the top 3 players from that pool of money
4.) I would have all of the details set far in advance so you can announce it ~1 month ahead of the event. So 2 months ahead of time?

first off for tables/prize support try reaching out to companies like Micro Arts, Deepcut, and Game Mat EU. See if they can provide anything.

Have a fall back for your tables, max 8 tables, do you want them all to be unique, how much terrain is needed. Break it down how much area terrain and linear terrain do you want per table. Drawing out plans for them helps so you know what is needed.

How much do you have already, is it part of a club set up or are you building everything from scratch? If it all has to be built from scratch simple is better to make both the build and repetition smoother.

Table wise, visiting a craft store or upholsterer to pick up cheap fabric works well to cover tables.

If you’re having to pay for the venue price the tickets at roughly two thirds capacity, by that I mean if you’re aiming for 16 players assume only 12 will turn up. Price the tickets to cover the venue at 12, if you get the full 16 then the other 4 tickets can go towards either the prize fund or be put towards terrain and the like for your next tournament.