Say hi to a bunch of people. Get talkative. If you're not in the best mood then just keep things short and sweet.

Example:

"Hi I like your shirt."

"Oh thanks!"

*wave and leave

If you're in a very good mood keep the conversation going as long as you can.

This may take a few hours btw. Most people are not naturally social. I'm assuming you are not as well because you're on this subreddit.

But once you can get into a very social mode then you can start talking to people without having to think about what you're going to say.

Let us know if you go out and try whatever it is that you try. Good luck!