How do I learn patience and to not rush in?

It's never easy to find the right moment necessarily, but you can usually tell if someone is into you by their actions and words. Do they make a point to talk with you and want to do things or at least make an effort to try and spend some time with you? Usually this is a good sign that they're into you. If this more along the lines of a "ask for their number" or "ask to hang out" kind of thing, best thing is to just ask when you have an opportunity you're comfortable with. Some people can't always see someone is into them without it being obvious or out right asking. Rejection will happen sometimes, but you'll never know if you don't take the shot.