The younger your pet is; the easier it will begin its crate training. Crate training can be made simple; if you begin when they are only about 8 to 10 months old. If you give them a chance to get used to being in the crate without it going anywhere, they will begin to trust that it is a safe place to be, and that is the beginning of their training.
Crate training is possible for older pets too. It takes a lot more patience and will require you to be consistent at all times. If you are too inconsistent with their training they will never trust it and therefore; it may never get easier to load them into it. After all, that is what you are trying to get them to do right? Train your pets to walk into the crate without having to make it a two-person job. Have one person hold the crate still while the other person drops your poor, scared animal into it.
There are several books available on crate training. You may want to buy one that will teach you a few techniques that may make it easier when you are training your pet. The best thing that I have found is to leave the cage in one spot with the door open. Let your pet explore the inside of it. Put in an old blanket and his favorite toys. Leave it in a fairly quiet spot for a few days before you need to put him in it. If he gets used to napping in it, it may make it easier for you when you need to load him into it. Have patience with your pet, one day he will be willing to walk into his cage if you train him right the first time.