Crate training worked wonders for me. My current yorkie is my very first dog EVER so I was flip flopping between different techniques, but crate training definitely did a lot. At night, I would put her in and she would let me know when she was awake and when she needed to go. However one night though, she refused to go in her crate.......and she's been on the bed at night with me ever since
That was when she was really young. Once she got a little older, I tried the bell training technique and to my surprise, she picked up on it within 2 days. BUT I did that when she got closer to being a year old. All in all, I highly recommend the crate training.