The biggest thing that helps me is containment, as catnapper said. Crating is great and works very quickly, but not all adopted dogs will take to it. Another thing to do is when you are home, contain the dog in a room where you are and let him out frequently, praising for every time he goes outside. I have had to do both with two different adoptees and both ways worked. Crating is faster, though. If you can crate train, do it. It may feel mean to keep the dog contained on occasion, but having a well trained dog is not mean at all. It will be a blessing to you, your pup, and your family! Most dogs love thier crate after the first week or so, it becomes a safe place.

My experience has also been that if you catch an older pup "in the act" once or twice, loudly distract them and get them to go immediately outside and give lots of praise, that usually "cures" peeing in the house. I know it is not always that easy, though, I have been lucky. He may have been housebroken but is confused by new surroundings and just needs some reminders.

Good luck!