Here is a quick, 3 minute tutorial on those tricky transitions from high plank to low plank (chaturanga) and then into cobra or updog. This transition is the one I most often see done incorrectly. If repeatedly done with poor alignment, this can lead to injury over time.
The key tips included are:
Shoulders forward of the wrist in the high plank position.
Lower chest before hips, never hips before chest.
Point your elbows back towards your knees, not winging out to the side.
Drop your knees down if you are tired, building upper body strength or just want a gentler practice.
Other pointers not covered in the video:
It goes without saying that core and thighs should be engaged.
Press firmly into the hands and draw the shoulder blades towards each other.
Broaden through the chest, don't allow it to collapse inward.
Keep drawing your pubic bone up towards your sternum and your front ribs towards each other.