Good point Rudo. I agree.
I wouldn't consider entering into MMA competition until I understood from a boxing perspective and a Muay Thai perspective as well. It adds the dirty boxing elements such as clinching, elbow strikes, etc. That would be the bare bones to a decent MMA stand up game. I don't know what you would like to add on top of that though to round out your stand up.
How about slick ground games? Freestyle Wrestling, Jiu-jitsu, would be the basics. Wrestling to learn how to fight from the top and jiu-jitsu to learn how to fight from the bottom.