Mom’s voice reverberates in my brain whenever I have to choose between may or can. May speaks to permission (“May I go to Janie’s?” “No, not until you do your homework”), whereas can speaks to ability (“Can I go to Janie’s?” “No, your leg is broken”). Nowadays that distinction is fading. Sorry, Mom.
But what about when may speaks to possibility, as in “I may [possibly] go to the writers conference”? What’s the difference between saying “I may go to the writers conference” and “I might go to the writers conference”?
Use may when the possibility is very likely. Use might when the possibility is mighty iffy.
So if you asked me if I were going to the writers conference, I’d respond—
“I may go,” if the possibility exists (I have the time and money) and I actually want to go, but … I need to finish my manuscript first, so I’m not sure.
“I might go,” if the possibility is less likely (I have another commitment I’d have to get out of first) or, truth to tell, I’m mighty shy and won’t go unless I have a friend to tag along with.
Okay, most of your friends won’t have a clue about the difference, but as a writer you should know … and, of course, use correct grammar.