It always blows me away that daycares get 1 year olds to sleep on cots. They stay there... how??? I suspect they are following what the older kids in the class are doing and they are never left alone. That makes it easier on many levels. Parents don't have that luxury at home when transitioning to the big kid bed.
Parents can get the child excited about leaving the security of the crib by talking about the bed before it is used. Have kids help pick out sheets or a pillow for the bed. Remind them during the day how big they are when they ___ (fill in the blank with "use a spoon," "pick up a toy," etc). Warning: This can backfire if they really are afraid of the bed and they do want to not be big, so they stop all the "big kid" behaviors.
If kids are afraid of their new bed, lay together to read books at nap and bed time. If you still have the crib available, ask if they want to sleep in the bed or the crib. Simply having the choice might empower them to want to stay in the bed. Feel free to leave a light or night light on in the hall (or even in the room if they prefer). Eventually they won't need it, but it can really help if they want it! Go through a routine of checking the closet (then closing the closet door), checking under the bed, and picking a favorite toy to be there while your child sleeps. It is amazing how much the power of suggestion that a stuffed toy will stay with them works! Let them know you will check on them soon... and do, but wait a little longer each night until they are asleep when you check.
For kids who are prone to falling out of bed, decide what works best for that child. Some parents put the mattress on the floor, so if they roll off it is no big deal. Many parents use bed rails that keep kids in the bed. Unfortunately if they roll hard enough, they can get trapped between the mattress and bed rail. I know this from experience! My son would do that and it would FREAK him out. He usually went to sleep without much fuss, but after he would get stuck in the rails he was too scared to sleep. We finally just put the bed against one wall and moved everything away from the other side of the bed except a nice layer of pillows and blankets. When he fell out of bed (yes, most nights...) he landed on the pillow pile and kept sleeping. Problem solved!
Pick a reasonable bed time. Account for all the time it will take to do all the stall tactics when picking the bedtime. If sleep time needs to be by 7:30, and you know they will resist brushing teeth, need to potty a 2nd time, get a drink, check the closet and under the bed, and read 3 books... get started in plenty of time to do all of that and still have them tucked in for the last time before 7:30. Ironically as kids get more tired, they get more wired, so DO NOT allow this process to run too late! They will hit a 2nd wind and be up far too long. We all know what kind of day tomorrow will be if they are up too late tonight... and it isn't pretty! Then they are over tired for the routine the next night, which can lead to an earlier 2nd wind and more troubles!
One trick I've learned that works well for older toddlers and preschoolers is the card trick. They start each night with 3 cards. Every time they leave their bed for another hug, a drink, to potty, etc, they surrender a card to you. Once all 3 cards are gone, they can't leave the bed any more. If they have cards left over in the morning, they get a sticker for each card. They can earn up to 3 stickers (or make it special to get an extra sticker if they have all 3 cards!) When they reach a set number of stickers they earn a prize. Go over the rules of the cards and stickers during the day several times so they know the rules before you start the system. At bedtime minimize the talking and just let them figure it out when you ask for cards or refuse to let them have a 4th resistance tactic. You can use cards from a regular deck, or you can make it even more fun by having your child make his own cards. I also suggest making a simple sticker reward chart, keeping in mind how difficult you think it will be to earn stickers and set a realistic goal for all the needed stickers to be earned within a week. If they don't earn the prize fast enough at the beginning they might lose interest (but it needs to be enough time that they earn it). You can make it more difficult over time, as their bedtime routine gets better. Remember that each day is new, so they start with 3 cards and you can talk up how much you know they can keep them all! Praise all the good choices, and if they struggle with it try to find positives to praise... "You kept your cards a little longer last night. I can tell you're working on keeping them all night!" For ideas of reward charts and cards, check out this fantastic free site!
If kids end up in your bed in the middle of the night and you don't want them there, you must firmly but without much discussion bring them back to their room. Too much snuggling, talking, or other interactions will only reinforce them coming to you again. And again. Night after night they get to spend more time with you-- that's what they see every time you give them attention when you need to limit the interaction. Attempt to get them to walk themselves, but if they refuse, carry them with outstretched arms facing away from you to decrease body contact.
If you don't mind them in your bed, be sure you are ready for a long term commitment to a family bed because once the habit's started it will be harder to break until the child wants to sleep independently. I learned this the hard way. Sleep deprivation makes parents do things they never thought they would... in the beginning you just want to get sleep. After awhile I realized I was kicked and punched often throughout the night by my lovely little angel who was not a great bedfellow. She affected my quality of sleep for quite awhile. I still love her greatly...If all else fails, talk to your child's doctor about sleep problems. Some sleep problems are due to real medical conditions and these should be evaluated. If sleep problems continue, loss of sleep can affect growth, learning, behavior, and more... don't let it get to that point!