Your coach will set it up. You can go indy, esp in the states where there more open with that, but the chance of getting mismatched is pretty huge there.
You usally have a "buy" on weight classes, most orgs usually have a 0.5-2lb grace. Most of the time its 1lb
My coach usually has us compete in both striking and grappling before even allowing us to do MMA. The minimum for us is 2-3 MT/KB fights or exhibitions, 2-3 BJJ tourneys. We all like the glory of stepping up and fighting, but this is a serious sport. The likelihood of injury is pretty high despite training alot. Not only is the gym's reputation on the line, but your health as well. Seen people go into competing absolutely unprepared and it was disgusting. Fuck those coaches. One event I was at, the guy after getting hit, turned to his side, and got hit midway of the other guy's combo, he ended up taking hard shots to his blindspot and was a punching bag for the good amount.
Now I haven't competed in MMA yet, but I have competed in MT a few times. As for nerves, I hate to sound generic, but we all deal with it differently. We all get nervous as shit before, and during the camp and event, but for me, once I do the walk out, and hop into the ring, it calms and its gone. Prior to that its nerve wrecking time, esp. when the shirt comes off and I gotta warm up.
It goes:
- hate life before weigh ins esp since I cut alot of weight.. for my standards (12-16lbs)
- love life while rehydrating and eating
- chilled out
- get nervous as shit because for some reason I can't sleep
- next day (or 5h later if its a same day event)
- -"hey J123, time to warm up, you're up in 2 fights"
- wrap up + shirt comes off
- "fuck...."
- I feel the cold sweat going down and get stupid thinking about "oh fuck, the guy warming up in the room across from me is drilling fancy hook kick spinning vagina #metoo sweeps, I didn't do that all camp. I'm fucked!"
- wait a bit, walk out
- calm and everything is nice and silent. Feels like heaven. Then we stare down, and I hate life again. I'm ready to go and bang, and you're wasting my time introducing us? motherfucker, we both know who everyone is, the crowd is full of supporters from our gyms, e all know each other. Just let us bang mang!!!
- then the bell rings, and its heaven again. The adrenaline has peaked at this point and I'm running on auto pilot. Feels great I don't feel pain, feels numbing
- 1min after the fight ends, everywhere hurts
- I eat junk food like a madman
- 4h later I fuck some escorts at night, and hope its not a robbery setup because I'm fucked all over and probably couldn't even defend myself against a 10 year old at this point.
Basically for the span of 3h, I'm going bipolar in nervous, calm, nervous, calm, over and over and over.
Don't rely on the referee to "save" you, half those guys that ref are fucking bums that hates it. First sanctioned MT event I was at, the guy really didn't give a crap. Chicka got wrecked and was turned into a human meatbag. Ref asks if she wanted to stop, she nodded her head yes, and he was like okay, continue on guys. She gets beat for another 1.5 min, then he stops it. Seen ones at grappling tourneys where the guy gets an armbar and nearly rips the arm out, ref looks like he's stoned, guy getting wrecked is tapping like a madman, the attacker is holding it because you know if he lets go, and the ref say "I didn't see it!" he's lost a huge chance and gotta start from scratch. So one guy is trying to hold / snap the arm, the other guy is for his life trying to make sure it aint coming off even though it will, and part time volunteer bum life ref is thinking about Tatjana the 5'8 ruskie whore who he wants to bang in 2 hours.