How to prepare for interviews?

Hi,

I am a developer in India and have been working with mainly Python in the backend - though I also work on the front-end. I have also developed complete production-level apps as a freelancer. I also have some very basic work on my Github.

I am trying for a job in the US. I've had 2 interviews but it didn't work out though according to me, one of them went really well. I think I am not prepared enough for interviews. My question is - How do I prepare for interviews before I start trying again?