So I have put countless hours into learning lots of tricks to beat defenders, I am very good on my feet, fast, good touch, but whenever I get 1 on 1 with a defender I freeze up and don't know what to do and usually automatically go to the simple backwards L, even if it's not the right thing to do.
From a coach's point of view: remember why you play football. Your problem appears to be less about skill and more about your stress.
Beyond practice; pick an upcoming game and beforehand decide you're going to go after the defender every chance you get. Explain this to your coach and let him/her know so you have an ally. If you are a forward, this should be expected. In fact, I will even advise you to lose the ball the first few times. How? Allow yourself to just experiment and hold up the defender - don't over-think it. The only skill advice I will add is be good with both feet.
Get the defender out of your head. Smile; be creative fluid and fast. Once you've lost a couple of battles (and likely won a few), keep going after them. Once the stress is gone, you will enhance your team. You have to want the challenge.
Here's the perspective from a defender:
What you want to accomplish is to get the defender to commit to a movement. Sign of a quality in a defender is to choose his/her timing to commit to a particular movement; regardless if that's a block, a slide tackle or simply closing a particular angle.
In a 1-on-1 situation with a defender (D), one of three things might happen;
D will rush on you, pressing you to make a move: in which case you make your move (as you said you are skilled, trained and have the flair to just avoid being tackled and proceed.
In a scenario where the D is a bit better/seasoned, he'll likely back up slowly while trying to close of your advancement, waiting for you to "make your move". In that case you need to someone get the defender to act and commit to something. If he commits, then you change direction/do something else.
For instance you might show/feint a shot stance, if he goes for it you just put the ball past the defender and quickly run past him. If he doesn't go for it, then by all means take the shot :)
Another option would be to show/feint dribble to one direction and suddenly change your direction. The linked video shows several different types of such movement, carried out by one of the best players out there. I linked the video to give you an idea on the movements involved, not to tell you to play like Messi, obviously. :)
In the unlikely case where the D stays his ground, just sprint past him (assuming that you have the speed, and space behind the D). You are coming with speed and you are the one choosing the direction of the play, so you have the advantage.
Besides the basic concept above, there is the mental aspect of the game. I have never been a good dribbler so I cannot tell you how you avoid "freezing up". I can only say that the moments where I somehow out-played the defender against me, is when I was too tired or caught-up-in-the-moment to think what I was gonna do, but just did it. It works wonders, not thinking but just doing.
So my best advice is out of a Nike ad: "JUST DO IT" :)
You weren't specific as to your question. Are you asking what should you actually do in that situation, or how you should improve your reaction to defenders?
If the first, it depends on the situation and the defender you're facing. Good defenders will try to force you to the outside, which means that's the easier way to go, but then you're generally looking to cross the ball, not shoot it yourself. A fake to the outside can sometimes draw a reaction, or rolling your foot across the top of the ball and quickly reversing direction may get you around him. Attackers can sometimes put the ball between the defenders legs, or if you have support a simple give and go can also work. There isn't one solution to this, since it's so situation dependent.
If you're asking how to improve, then you should find a defender who wants to practice his/her defense and go practice with them. In practice, decide what you're going to try beforehand so you don't have to make the instantaneous decision. Practice a move 5-10 times, then another move 5-10 times, then another move 5-10 times, then cycle back around and try the first one again. You can start off with a "dummy" defender - just put out a box or a backpack to mark where the defender is until you get the moves down. Then bring in someone live who will actually respond to you. Once you've practiced it a lot outside of the game, it'll make a big difference in the game.
Once in the game, pay attention to the defender's body language. If they are trying to force you to the outside, their body will be angled upfield so that they can more easily cut in (but not as easily cut out). If they're looking to slow you down, they'll be facing you about 1-2 yards away. If they're challenging you directly, they'll be approaching close. The situation will help you make the decision. Defenders in motion can be more easily cut around with a small move backwards or to the side. Charging defenders most often warrant a give and go, but if you're good with you feet you can get around them yourself. A defender who's trying to force you out may warrant just taking the outside and putting a cross in, but only if you have support in the box.
Best advice is.. Read the situation. In football being one on one with a defender doesn't mean just go and attack him. End of the day you don't want to lose the ball and be on the back of that. For example: Read the game if you see a player free, play the ball. Drag your defender towards him.
Then take the ball back when in free situation and take it forward.
Move in to positions where defender forgets to mark you then ask for the ball. The defence will already be out of position allowing you to move forward into attacking position. Making it easier for you to dribble at defenders and stopping you from freezing.
Taking players on is great, but positioning is vital. If your in a better position from the start you already got the upper hand.. Less likely for you to just 'freeze up' As a player who used run at defenders. Over the years when you play against quicker and strong defenders. You can't simply just skip past them, but you had to position yourself to do it right. Get the defender facing side on.. Dribble one way then change. Making it a lot harder for the defender to get back because of his/her positioning.
Alright so what I would usually do is take me right foot and motion that I'm going right but actually just draw it over the ball the take it back to my left. Usually works for me. The follow your body movements so when you take it back to your left foot it gives you time to shift your weight quickly depending on your side. Can be reversed depending on the dominant foot.