If you haven't read it, pick up "How to Win Friends and Influence People" - it's the best book on interpersonal skills you're likely to find. One of the key points in there is that people love to talk about themselves. If you want to impress someone you've just met, start asking them questions about themselves, and be genuinely interested in what they have to say. When you part ways, that person is likely going to think you're a great conversationalist, even if you hardly said a word about yourself.
In other words, you're an interesting person if you're interested in them.
If you have difficulty making eye contact with people when you're speaking to them, practice it over and over again until it becomes natural. This was tough for me at first; I had to practice a lot. I tended to start the conversation making eye contact but then dropping my gaze, looking away, or glancing over the shoulder of the person I was speaking to.
Eye contact is a powerful thing, especially if you're trying to be persuasive. And persuasion is an important part of business, even if you're not in sales and even if you're a software developer.
Could you elaborate why why that is the case?