Everyday you are negotiating whether you realize it or not. You negotiate with your family, your friends, and your collegues. It is a skill that combines logic and emotions. The way that you feel in your gut is usually 50% of your equation and 50% experience. We have all had at least one moment when we ignored our gut instincts, only to regret it later. It's a learning curve forgive yourself and learn from your mistakes. Success is 90% failure and 10% getting it right. The value of that 10% can be limitless so don't let that number depress you.
I have made more mistakes than I can even recall. Move forward from your mistakes, don't allow them to lock you in fear or you will never grow. Take calculated and educated risks!
When it comes time to invlove yourself in a bigger deal with another company make sure you bring more to the table than they expect. This is how deals become legends. What sets you apart from your competition? How can you use that something extra to sell yourself? Don't just go into it with $ signs in your eyes, think about a bigger opportunity than can be born from that deal. See yourself as their partner and tell them this is what I can do for you.