Crate training is a great way to go. It gives them a safe place to sleep, and it helps tremendously with housebreaking. You will definitely find that an x-pen will help out. What I did in the early days was put her crate in an x-pen. She slept with the crate door opened, and pee pads at one end of the x-pen. This way, she could get up in the night to relieve herself. After several weeks, we found that she was no longer using the pads in the night. That is when we started closing the door on her crate at night. The first night we did this, she had an accident in the crate. So we cleaned it up, and went one more week with the crate door open. Then we tried it again. We had success! Since then, she has slept in the crate with no accidents.
Here's a picture of the set up we used: |