I've always thought it very useful with dogs that are light enough to be picked up to have a safe method of doing it. It's important that the dog is used to it and knows what to expect, so it needs to be practiced. My method: Squat down but keep your back straight. Assuming you are facing the left side of the dog, so its head is to your left. Put your left arm under the dog's chest with your hand facing upwards. This means turning your arm anticlockwise. With your left hand hold the dog's front right leg quite firmly just below the shoulder. At this stage it's awkward for you because your arm is turned as far anticlockwise as far as it will go. Simultaneously sweep your right arm leftwards towards the dog's bum, holding down the tail. Your arm will then be supporting the dog at the top of the back legs/bum area. Stand up keeping your back straight, and lifting the dog. Lift the front of the dog higher than the back. That allows your arm to rotate clockwise to a more comfortable position. The dog's weight should be roughly the same on both of your arms. The dog should be comfortable because its weight is on naturally load-bearing parts: the bum/back legs and the front shoulders, rather than on the chest. I don't know anyone else who lifts dogs this way but it works for me. When I took Bella to the vets he was surprised at how easily I lifted her onto the table and how calm she was about it. It does depend very much on the dog being used to it though. My old labs used to come to me when we reached an obstruction on a walk and ask to be lifted over. I couldn't lift a lab now though! Bella is just about capable of climbing in and out of the van but will scrounge a lift if she can get away with it. (She tried to be a stowaway the other day; attempted to jump into the back of the van when I wasn't looking. It ended ignominiously for her.)
Bill