Hi M.!
I have a 3.5 yo daughter who is potty trained! I hear girls are usually easier than boys... but you never know!
What I did was introduce the potty by video first. She was really into sesame street, and elmo has a potty movie that we watched a few times. Theny I bought her one and left it in the living room (where we mostly are). I mentioned the goal to day care and they were all about helping out!
Then one weekend when we had NO PLANS I told her we weren't using any diapers cause we ran out... I would have to get some at the store later and just put her in undies. We had several accidents that day, but it seemed to get her in the state that she didn't want to be wet. That night I "found" one diaper and she could use that to sleep. Then the next day the same thing... That next week in school she was asked a couple of times an hour, sometimes she would go... sometimes she was wet. Then we did the same thing that following weekend and it clicked. She definatly had a few accidents, but the practice was coming along and she liked her big girl potty. Every time she sat and went pee, she got a sticker. If she went #2, she got 2 stickers and after 10 stickers she got a small prize @ the stoer. I know at school if the kids sit on the potty they got 1 m&m, if they went pee they got 5.
I would say try anything and everything and just keep praising them!! To this day, my dd still gets so excited when she goes and makes us come into the bathroom to see what she did! It's funny!!
Good Luck!
~ T.