If the block start feels unnatural, you can try this drill to help you position your hip during your first steps. I use this drill in my warm-up to get the right feeling for the movement. The drill is especially useful for teenagers who have the strength to utilize the blocks but do not feel comfortable pushing violently against them. You can go back and forth between the falling start drill and the regular block start until you reach the same natural motion. The black and white stills in the below video is to check if this is true for me.
The falling start resembles a swimmer's start. It will take a bit of courage to fully extend the body with the hip and shoulders close enough to the ground to produce force horizontally rather than vertically. I highly recommend you film your block start as your head position might give you a false feeling of your body's position. At least this is the case for me :)
Also, you can try to use the so called toe drag, letting your toes swipe the ground during the first steps, to help you keep your body tilted.
Let me know how your experiments with the hip positioning goes. Drop a comment on Facebook and let's compare notes.
Learn more about speed and strength training by downloading the Outdoor Edition Training Guide. Also, be on the look out for the Fit Businessman book by Eric Snaell.