Make it a positive experience, starting with only a few minutes at a time at first, working your way up to longer periods of time. Put in toys or special treats that they love but only get during crate time. If they are whining or barking don’t let them out until they stop. Otherwise this reinforces to them that if they bark or whine you will let them out. Once they stop barking/whining then let them out and give them lots of praise. Never use a crate as punishment.
A puppy should only be left in a crate for a maximum of one hour per month of age. If you are going to be gone longer than that then leave them in a play pen or exercise pen or laundry room with a gate so they have more room.
Covering with a blanket helps it feel more like a den, but leave one side open, they like to be able to see out.
Smart Pet Love Snuggle Puppy (available on Amazon) is very effective. It is a stuffed animal dog that has a heartbeat and warming pad in it to help them not feel as lonely in their crate.
If you don’t want to use the Snuggle Puppy then you can use a microwaveable rice/flax seed bag to warm and put in their crate, it can soothe them by giving warmth like their litter mates. Just make sure that they have room to get away from it if they get too warm. This is also great for after their bath to help them stay warm.
Make sure they only have room in their crate to lay down, get up and turn around, but not enough room to go potty. Choose the size of crate that your puppy will need once they reach their adult size, and just use the divider that comes with the crate to keep the area small that they will be using.
The first few nights with you they will be scared and need more reassurance and patience. I like to put their crate on a chair by my bed. This way if they are whining or crying during the night I simply reach the crate and pet them for a few minutes. They usually calm down pretty quickly. If they are persistent then take them out to the bathroom, then straight back into the crate. After they adjust to being in their new home you can work on moving the crate away from your bed.