I havent read all the replies so sorry if I dont offer anything new! Here's what we did -DD was 19mths old.
She was moving rooms and moving into a bed, so we took her shopping to buy new sheets/doona etc and made a big deal of it. Then set her new room up over a few weeks, and would talk about her "big girl bed in her big girl room" and go in there and read stories etc sometimes.
Then when it came time to sleep in there we put her cot in the room to help her transition - but she just wanted to sleep in the bed! So that was it - no dramas

HTH, and good luck!