People LOVE to talk, so let them. Ask them questions! And LISTEN, so it can help you ask your next question.
1:1 on conversations can feel like a lot of pressure. Include someone else to your conversation. This will helps things flow a little easier.
Complimenting someone is a good way to start a conversation. It breaks the ice really quickly if you don't know what to say.
For example, if you just got a puppy, talk about the puppy. Everyone loves dogs and they want to know how puppy life is going!
It's important to look interested and friendly. Smile, nod, eye contact, and genuinely try to make that person you are talking to feel important.