I won the state title in MMA. If I were to be in a fight, I wouldn't even remember 1% of my MMA training. I'd throw dirt in their face, knee them to the nuts then pull their shirt over their head and stomp their kneecaps. Or something similarly dirty and disabling. This is because I lived on the streets on and off for 3 years.
Just to lay it out for you, martial arts are a sport. In a real fight even a punch isn't that applicable. You want to hit them with fingers to the throat/eyes with speed an accuracy, not power. You don't want to knock them out (it's way harder than you think in real life) or get them in a hold like most martial arts. You don't want to submit them. You want to disable them; which means they have to lose their sight, hearing, breathing, legs, arms or just take a vicious beating. The last is cruel though. It's better to just hurt a leg or an arm really bad.
Martial Arts helps you get over the adrenaline rush of being hit, but I've seen a lot of TKD and Karate kids freeze up after getting a real 100% punch to the face, so I know it isn't enough. Once at primary school this black-belt in kung-fu got the **** beaten out of him by the most athletic kid. The kid just kicked him in the nuts and started wailing on him while he was down. **** fighting dirty, either talk your way out of it (best option), run (next best) or hurt them badly so they can't respond and hurt you. Especially if there is more than one. Most people won't fight a guy who just brutally blinded their biggest friend. Always hurt the biggest guy first.
Here are the three best tips I ever got given:
1) Distract them. Start crying, throw something at their face (so they go to catch it), yell for your friends.
2) Hit them in the testicles as hard as you can. If they don't drop to the floor, stomp a kneecap so they do.
3) Run. You don't know where his friends are.
If you really want to learn, go to Krav Maga or if possible, get a marine/green beret/SAS guy to show you. They actually learn how to fight for their lives. Cops learn how to restrain, not useful against guys bigger/more drugged up who really want to hurt you unless you outnumber them/have a gun/have a taser.