How you train is how you fight - I've heard that adage from a number of instructors in my past and, as it goes, I now attempt to pass on that same knowledge to my students. In my experience as a muay thai instructor, approximately 50% of students have studied another form of martial arts, mostly sport muay thai, taekwondo, or jujitsu.
I train and teach lerd rit, muay boran, and muay chao cherk for the purposes of street defense, not for cultural demonstrations. A high percentage of our training is focused on multiple opponents, and I teach that when you strike, you strike to demolish, not to score points. My school (I teach there, I'm not the owner), Muay Thai Academy International does not participate in competition mainly because we don't we don't believe in watering down technique for ring or cage application.
I've seen that most western martial artists are trained to strike targets in the hopes of scoring points, or applying a form because its the "proper technique", not because it generates maximum force.
If you're training a martial art, specifically muay thai, and you find that you throw round kicks to the head more often than not, your switch kick is all but useless, and you believe that the purpose for an elbow is to cut your opponent's eye I have some bad news for you. All that training at your camps or gyms may be for naught in a real fight in the streets. You're training to win a competition, not to survive an attack in a situation where there is no referee, no bell, no one to throw in the towel if things go south. Are you really going to go to the ground against 2 or 3 guys? Just remember that the habits you form in the gym are the same habits you'll take with you into a confrontation. Now I know I'll probably get some unsavory responses for this post, and that's fine. Agree to disagree, right?
If you're still reading this and you're considering augmenting your training to apply your existing skill set for street defense, here are a few things to think about:
1. Aim for big targets: Forget about trying to hit someone in the jaw for a knockout. The head is a small target that's difficult to hit. Imagine an invisible triangle starting at the jaw and expanding down to right above the pectorals. You have a much better chance of hitting that area which contains the throat, clavicals and large nerve masses. Think center body mass.
2. Don't hit, smash: When you strike, strike through your opponent, don't just hit. For example, when doing thai pad drills, visualize your kick / elbow / knee going right through the pad holder, knocking him back.
3. Your attacker is one big target: Take the human out of the equation. You could be fighting for your life and your attacker won't certainly be treating you like a sparring partner. You need not care about his/her feelings. No more, "oops, I threw that one a little too hard."
3. No more rules: Eye gouging, biting, groin shots, head butts, and weapons are now allowed. Train accordingly. Here's a great source for info on unorthodox street defense.
4. Train in your street clothes in different environments, on different terrain. I've said before,
it's important that you're as comfortable fighting in slacks as you are in shorts. Set up staged situations such as an office, a living room, a dance floor complete with strobe lights and loud music. You'll soon learn how difficult it is to defend and attack with multiple distractions and obstacles.
5. Improvise: Learn how to fight with what what you have around you. Almost anything can be used as either a weapon or as a defense tool, and then a weapon.
6. Multiple baddies: Start to put it into your head that you may be facing more than one opponent. In reality, more often than not you'll end up against 2-5 attackers.
Those are a few basics to think about and when integrated into your regular training regimen, you'll find that you're getting a lot more out of your martial arts experience.