This is just an example of how to modify a push up to get proper range and form, as many do not have the strength of to a flat push up. Start in a push up position, tighten the core and externally rotate the shoulders feeling a pinch in the shoulder blades. Bend the arms tight to the body (targeting triceps), or wider hand stance (targeting chest) depending on your goal. breathe out at towards the top of the rep.
Helpful tips and Tricks
You can do this super slow, or explosive, depending on your specific goal. You can use anything from a smith machine or desk to get the right angle.