Some brief advice:
* The best way to understand the opposite sex is to first learn to truly understand yourself
* NEVER look to someone else to make you feel happy
* You can NEVER truly make someone else feel happy, and, even though your mind may tell you they can, no one else can ever truly make you happy. Happiness is an inside job.
* It becomes EASY to approach the opposite sex, when you understand yourself and have truly come to understand that happiness is an inside job. Until you grasp this, you'll believe you 'need' a partner, and this belief will make you also believe that 'the stakes are high', and if you believe that they stakes are high, then of course you are going to feel tense and nervous about approaching potential partners.
* A different way of saying this is that relationships (and friendships) are paradoxical; the less you 'need' someone in order to feel contented/happy/peaceful, the more others will be attracted to you.
* Until you have learned to be happy in yourself, you will never have a truly healthy relationship with another person. Failure to understand this will lead to neediness, or jealousy, or insecurity, or any of a whole host of other maladaptive psychological behaviours. Remarkably few human beings grasp this simple fact, even after a whole lifetime.