How do I get my son to hold his crayon/pencil right?

triangular crayons and finger positioning grips will help. Finger and hand strength also has a lot to do with it. PLay dough, silly putty and even wheel barrow races help with that end.

my daughter had the same problem, her teacher at preschool used to put the pencil in front of my daughter with the tip facing her as they pick it up they wil naturally pick it up in the correct position, then its just trying to get them to keep it that way.

repetition? He'll figure it out soon.

Break the crayons. When it's small, it forces them to use the right grip. That's what multiple OTs have told me.

She's 3, she will get it. She has plenty of time to learn. I taught preschool for 20 years and 3 is a little young for some to hold the crayon or pencil correctly. Every child I taught was able to hold them correctly by the time they went to Kindergarten. Just keep showing her but don't push it. Some people (like me) never hold the pencil correctly. It ends up being what is most comfortable.