OK. So I have several years experience. started in wrestling and judo for several years. Then did BJJ, boxing and muay thai for 7 years.
The basics are really boxing and wrestling. I include Judo as jacketed wrestling in this. They will be cheaper and more realistic than BJJ or Muay thai. After all these years of BJJ, the submissions in Judo are still the most common (RNC, Gi chokes, bent and straight armbars, and pins and escapes) both in MMA and in street altercations.
The basic 4 punches are also the most encountered and easy to use in mixed footing. In a street encounter if you are forced to fight, you may not have room to kick. And honestly, you won't have the time to "cook" anyone on the ground BJJ style.
Your number 1 priority is to escape, run away and live. If you have to fight, run away if you have an avenue. If you are unable to escape, throw the guy on the ground and run. If you fall or are taken down, get up off the ground (pin escapes) and run. If you have to strike, footwork, the old 1-2 and run...
I can talk about MMA all day since I trained it for so long and have trained with so many ammy and mma fighters.
Bang for the buck techniques:
Striking: Jab, Cross,
Takedowns: Double leg, Body clinch
Escapes: Wrestling Stand up, BJJ technical stand up, Mount escapes, Side control escapes
Submissions: RNC, Guillotine, head and arm triangle (All can be done from standing)****
Nobody taps to joint locks in a real fight, they barely tap in MMA honestly. Chokes only..
If you have the time, I recommend the Southpaw podcast and program. They have a "Liberation Martial Arts" program that is made to facilitate group study without having to depend on an instructor. Most MMA and martial arts gyms are right wing both in atmosphere and philosophy, so the idea is to create a space that isn't hostile to leftists. And the creator is/was a BJJ instructor (black belt) and a Socialist.