I've used a crate for my puppy for the first time and will use it for any future puppies.
What i did on the first day was to encourage her into the crate - just made sure she walked forward into the crate - i then sat right next to the crate and blocked her from coming out, stroked her and she settled. Once she lay down i then closed the door.....i think its important that you dont shut the door till they are relaxed and not trying to escape. I then still sat next to the crate and the gradually sat further away till out of the door. For the next week i followed the same process and she settled quicker and quicker so now i can say sleeptime and she will go into the crate and lay down (shes nearly 4 months old). I only put her in though when she is tired - otherwise she is loose in the kitchen.
In terms of returning when she is crying - to me it depends on when she cries - ie if i close the door of the crate and leave the kitchen she may then cry which i do leave her and she settles back to sleep after a few minutes. When she wakes up she cries to tell me she wants to come out so i go to the crate and wait for her to sit and be quiet before i let her out..........
works for me anyway - i get up at 7.30am and although she is awake in her crate she hasnt cried at all to tell me to let her out...and the crate is wee / poo free too
