In gymnastics or in cheer-leading or acrobatics, the back tuck is a really fun skill to learn how to do. There are numerous different drills or progression techniques to use when you're doing this. A really good drill, which also would be the first drill we're talking about, would be to learn how to leave the ground. Learn how to jump, what the angle would be in order to flip over.
So a good drill is to set up a pretty decent sized mat stack, you would want to definitely want to learn how to swing your arms appropriately, getting them up on time, but initially jumping up, leaning back in the air, and lifting your hips upward, do that to initiate the flip. So from there, standing in front of the mat with the mat stack to your back, you would bend forward, swing your arms back, swing your arms up and jump, and kind of lift your hips and lean back a little bit, landing on your back at a slight angle. From there you learn how to do the same thing, but also tuck your knees and kick your feet over your head and do the backwards roll across the mat stack after you jump.
Another good technique would be to just have a nice spot, to where you would learn how it really feels to get a good flip going, and with the spot it is also safer for a landing.