Toddlers are typically ready to transition out of a crib between 18 months and 3 years of age, although some crafty climbers may need to move out earlier. Some parents might be concerned that a toddler bed is used only for a short period before moving on to a standard twin-sized bed. If that sounds like you, consider skipping the toddler bed completely. Toddler beds have come on the market relatively recently.
Purchase a quality mattress, box spring and frame. This bed could potentially last your child until he leaves for college, so you want it to be a decent one.
Set the bed up in your child's room. Involve him in the process as much as possible. Helping you out will help him to get excited about the new bed, and give him a sense of ownership.
Set up the bed rails. These typically slide between the mattress and box spring and then pop up alongside the bed. If the bed is against the wall, you don't need to put one on that side, but you will want two rails if it's not against a wall. Position the rails so you have about a foot of free space at the head of the bed; this will give your child a clear view to the side when lying on his pillow. It also allows the rails to stretch further down the bed. They typically leave about 2 feet open at the foot of the bed.
Make the bed with sheets your child has picked out. Letting him pick out the sheets and blankets gives a sense of excitement and ownership to the new bed.