I hated Oh Crap and thought it was a load of rubbish XD
It also didn't work for DS2 (I tried it anyway despite the scepticism because I wanted "a method".)
What worked for us was basically:
- Get some books about potty training - friends often have them to pass on because they are basically useless once you've trained. Read these to introduce the idea.
- Let her see you use the toilet, explain what you're doing and that big girls use the toilet and she will one day.
- Buy some underwear, preferably with characters that she likes, or let her choose her own.
- Get hold of lots of spare clothes and easy to pull up/down. (Doing it between sizes is a good idea because you have twice as many clothes)
- Buy or get hold of a potty and/or an insert for your toilet, and a step.
Then you can either do a more directed, parent-led intensive program where you block out a couple of days that you won't need to leave the house, optionally feed her a load of sugary enticing drinks like fruit shoot or capri sun, and then either leave her bottomless (I did think Oh Crap had some good info about how you'll start to spot their "potty signs") or put underwear and trousers/skirt on but keep bringing her to the toilet or potty every 15-30 minutes and get her to sit there for a few minutes by singing a song or reading a book. When she does something in the potty, praise. If you like you can do a small reward like a sticker or single chocolate button.
If she has an accident don't shame/punish. Try and get her to the potty ASAP (this is why a potty can help since you can move it around based on the room you're in) and try and catch at least a little bit on the potty - you can count that as a win.
Over time you get better at spotting and she gets better at holding on so you have fewer accidents and can phase out both potty and rewards if you've used rewards. If you're doing v intense with naked time and/or frequent potty visits then it should only be 2-3 days with a lot of accidents, you'll generally have a huge improvement by day 3/4 and be able to go out and about etc. You should expect accidents and short notice toilet needs for a little while though so may wish to plan trips out around the amount of time she's reliable for and/or easy access to nice, clean, child friendly toilets.
Or if you are happier with a slower approach you can just show her the underwear and the toilet/potty and give her the choice. This tends to lead to a later or less consistent start but fewer accidents and you don't need to do all the prompting or stay inside for days.
I would not bother with pull ups personally because they just feel like a nappy. We did switch to these at night though so that he can get himself ready for bed.