Belle loves to go for car rides. She jumps into my SUV or my husband's truck with no problems, but we don't let her jump down for fear of injury. When I pick her up, I put one arm across the front part of her chest to stabilize her and my other arm goes in front of her back legs. I don't like putting an arm behind her front legs because if she were to jump forward I would have a hard time stopping her. I dropped a small dog that way once
This link shows what I'm talking about. Sorry, it's hard to explain in words.
How to Pick up a Dog Properly: 3 Steps (with Pictures) - wikiHow