I once worked as a server in a restaurant. It was also around that time that I really started using bicycles as a means of transportation/utility rather than just leisure. In the restaurant, when lifting a heavy tray full of food/drinks, I was taught to crouch down to bring my shoulder near to the level of the tray on a stand. Then slide the tray off the stand, onto my hand, and rise up. This is sort of the “lift with your legs” approach for handling food trays. When upright you keep the elbow down and your forearm/hand up near your shoulder. This takes advantage of your skeletal structure and requires less muscle strength. Turned out the same method works great for hauling bikes. Though, because I was commuting, sometimes the bike was quite heavy with a grocery haul on the way home. This method, I find is better for lifting a heavy/laden bike than some of the other methods listed. So the grab spot is the top tube, just in front of the seat tube. You crouch down to bring your shoulder nearer to the height of the top tube. Elbow down along your side, same hand up near your shoulder holding the top tube from below. Stand up and stabilize handlebars with the non lifting hand.