Teaching a toddler to sleep alone in his own bed may become very difficult. Because the conceit or the protection of some parents, these allow them to sleep in his bed not knowing, perhaps, that they are doing great damage.
Only in some cases this may be acceptable. If a child is sick or wakes up in the middle of the night crying or scared, you can afford. But in reality there are many risks that can even cause sudden death and other tragedies, can drown or suffer a severe fall, and the worst is that he will practice and later will be more difficult to separate.
It is best to create you a routine and take it to bed as often as necessary, without a word, should always sleep at the same time with any object they like or means something special to them. The bed should always be in the same place and the bedroom should be decorated according to the taste of children, there must be toys or objects that you want and you know you wait in the same place always to accompany him to sleep.
Kids love to sleep with their parents, but if this becomes a habit and part of the routine, the consequences will not be at all rewarding in the future. From small they must instill notions of privacy. When they are small babies may be more affordable to share a bed, but after three years can cause the child becomes insecure and overly dependent.
If they have fear then they should be taught to overcome their fears by facing them and not fleeing from the situation. It takes time but with firmness and patience you can achieve the expected and have children very independent and confident from an early age.