You have a lot of good advice already and it is right on.
Things that worked for me and my neighbor- (between us we have 7 kids)
1. Let 'em run around half naked (they have a hard time with the whole pull 'em down and get on the potty in time thing).
2. Special bthrm things (for me it was books)
3. Staying in the bthrm with them the entire time no matter what (ignore phones, and take the baby with you even if it means feeding him in there or delaying feeding for 5 minutes)
4. Taking her every hour whether she wants to go or not, but only sit there for about 2 minutes--it is not an upleasant experience.
5. Taking them outside (only works in warm weather) in panties and letting them pee on themselves and leaving them like that. ugh. Sounds gross but they get the idea after awhile because they start itching and are uncomfortable. ;-)
6. Final straw- with my 3 1/2 yr old I just swatted his bottom one time if he had wet pants. He just could not be bothered to stop playing and go potty. So I made it become important to him. I swatted him and changed him and made a big deal of the times he went when I took him.
7. Buy special underoos, make a big deal out of it and then throw them away if they go poopoo in them. One kid was devasted about this and quit pooping in his special big boy pants.
8. Most important say 20x a day,,,tell mommy when you need to potty. LOL Sounds silly but it helps a ton!!
9. Limit drinks. Obviously a kid that drinks a ton is going to be needing to potty a lot too! That can work the opposite too--give her a ton of drink and then go potty every 30 minutes. LOL
Good luck,
ts