Hitting front lat spread and front double bicep, lift your rib cage, don't lean down...
good advice
and try to "pull" your arms away from your body in both poses
in back lat spread and back double biceps pull the lats / rhomboids A BIT towards the front
the best thing you can do is videotape yourself.
what helps tremendously is live videotaping yourself in REAL TIME through a camera and screen, so that you see exactly what happens when you move in a certain way. need equipment for this though (which i dont have either)