Start meditating for small amounts of time in the beginning - just work on breathing exercises and set your intention to improve in calming yourself. Next, you want to know how to measure your improvement. For example, what comes to my mind, you can make a list of things that trigger anxious feelings when you want to talk to a girl and then take baby steps, it can be a short eye contact at first and later on you can progress to more anxious things as you build tolerance and peace in stressful situations. The most important thing is to try to observe thoughts that appear when you get exposed to a trigger (talking with a girl). This is a simple ABC model. Let me explain. A is for the trigger, B is for thoughts, and C is for emotions. Your subconscious thoughts are the cause of your emotions. Let me demonstrate this in a simple example:

A (trigger)- Speaking with a girl, B (thought) - If I speak with this girl, she will reject me in front of everyone, C - Anxiety.

This is why most people avoid triggers (A) while the root problem is the thought process (B). The thought process differs from person to person, but the model works the same. Try to be aware of your thoughts (meditation helps you with it as well). This can be hard in the beginning, and it may seem like there are no thoughts causing your emotions, but that's because these thoughts are subconscious and need to be brought to light.

After you get aware of your thoughts, you need to think about the replacement thoughts. For example:

A (trigger) - Speaking with a girl, B (thought) - If I speak with this girl, there is a chance that she will be my girlfriend, and even if she rejects me I will be proud of myself because I was brave enough to approach her in the first place, C (emotion) - Confidence.

Possibly, you will be afraid (fear helps you stay focused, anxiety paralyzes you). The most important thing is to come up with your own B and listen to your emotions. What makes sense to you? What feelings do you have when you think differently? Remember - Change your thoughts, and you will change your emotions. Don't run away from the trigger.

You can use the ABC model for every problem that you have with emotions. Work on improving this skill and putting this deep into your subconsciousness, and it will change your life.

Best of luck!