If at all possible allow your child to be involved in the decision to move into the new bed and to help pick it out. If you already have the bed and purchasing a new one is not an option then consider letting your child pick out new sheets and covers for it. This will make it more their bed in their mind and make the change more positive for them.
Once you have the toddler bed set it up in the child's room for several weeks before you actually move them into it. This will give them an opportunity to get used to it so it will not seem so new. If you need to you can even start having the child get into the toddler bed each night as part of the bed time routine and lay in it for a little while. Maybe while you read them a story, and then move into their crib when to actually sleep. Move everything possible from the crib into the toddler bed to reduce the actual amount of change. You can try having them take their day time naps in the bed but still sleep in their crib at night. When you are actually ready to start using the toddler bed full time you should take down the crib and move the toddler bed into the same location in the room to ease the transition.
Patience is the order of the day especially if your child is reluctant to give up their crib. Some children take to their new big boy or big girl bed without any qualms but for many it is a very trying change. Try to avoid doing it at the same time there are any other changes happening in your toddlers life. If they are just starting potty training, changing day cares or the addition of a new family member.
No matter what you do your child may just not be ready for this change in which case you just need to be patient and wait a few months and try it again.
