Forget the 'random' part. That will automatically leave you unsure of yourself.
To start with, talk about things you know, with people who know the same things. Like activities you enjoy, books, films, whatever it may be. Are there any clubs you could join which cater for the things you like to do? People there will already have one thing in common with you and it can be used to break the ice, to get you feeling more comfortable talking to people in general.
It's largely a confidence thing, so once you build that up, the rest will follow naturally.
It might also be worth learning to read body language. That can tell you far more about a person than what they actually say.