You can definitely improve. Some people a naturally better at this, often there are cultural or class differences, for instance I noticed after a while people from UK public schools are much better at selling themselves and introductions.

Look at people when you meet them and talk, shake their hand (not at the moment!), remember and repeat their name, tell them your name and something about yourself, ask and listen to them talk about themselves family/interests. Followup on the conversation if you want to keep them in your network.

Oh and you can practice this lots. Talk to people in the street, in shops, in bars. I think I improved this a bit going backpacking for instance as you have to communicate with lots of new people often without a common language