Pongy“when do we use them”
Make it easy on yourself. Always use
might if you have a choice. Later, once you have mastered
might, if you want to write more formally or for some academic purpose, and you have a choice, use
may.
If it's a matter of permission, you don't have the choice. Use may in that case, or can. May I help you? Can I help you? You [may not / cannot] cross this line; the police are doing an investigation here.
CJ