ONe thing I have found that helped was the Doggy diapers/panties. I moved from a house with a fenced in yard to a condo myself and had to train Gracie to use a pee pad as well as being let outside. So I used the diapers because when we had a house she was use to being able to run around because she knew to use her doggy door and go outside to potty.
Now there is no doggy door and she has to learn to let me know when she needs to go out or to use the pad.
Maybe to help with the accidents put a panty or diaper on her til she gets "it"
As for the training I say the crate is a good method...thats what I plan to do with my new puppy Chloe.