Photography

My question is basically the title itself, but if I have to give more context, I'd say:

I really love raw/natural pictures: smiles, persons, laughs, lights, landscapes, scenes... And sometimes I can capture these moments but sometimes I miss my shot and want to "redo" it when I take a picture of someone. The thing is, once I ask them if I can take a picture of them, their body just, just does not act as natural. Some people (including me) do not know what to do with their body in front of a camera, so they often just stand up straight. I figured out something (maybe) that kinda works: I make them laugh or I ask them to do somthing that requires more movement, like jumping, but you can guess that I'm not always funny or I do not always have something to say, or I do not always want my subject to jump.

So please I'd really like some advices/tips/help