Practice to Session 1 from David's all level video course, Finishing Backbends of Ashtanga Yoga. In every class David breaks down Urdhva Dhanurasana, Drop Backs, Tic Tacs, and the Final Backend, Each class gets progressively more and more challenging.
In session 1 you will do these exercises:

1-UPWARD BOW
A) Introduce the classic position
B) Setu Bandhasana exercise with 3 leg actions
C) Come up onto your head and get knees vertical over the ankles, adduct, internally rotate, and fix legs in position.
D) Up into Urdhva Dhanurasana, get knees vertical over the ankles, adduct, internally rotate and fix in position.
E) Introduce the classic position focusing on arms
F) Come up work to get the shoulders, elbows and wrists in a vertical line

2- DROP BACK
A) Standing and making a beginning with Namaste hands.
B) Making a beginning with arms up

3- TIC TACS
A) In Head Balance starting to curve your spine and then going beyond vertical with straight legs
B) In Head balance jumping up and going beyond vertical by bending the knees and coming back up
C) Coming up and down in vertical position in Head Balance

4-FINAL BACKBEND
A) Three dips with arms crossed
B) Push up from the ground and hold