1st talent could go to vampiric rounds, but i just prefere the sleep dart improvement. u can 'vampiric rounds' if u want heal self better (but its not heavy enough incrase for me).

crucial talents are 4th and 7th talents. crucial for suppressing the dmg of enemies. especialy in teamfights. As i usualy set healers talents for better healing - as the role expects, its simple pleasure to see 2/3 enemies, both 5 doses that do so weak damage u can heal much more efective than they hit.

Playing this Ana:
Try to keep urself behind teammates. U actually cant heal self, meybe granade, meybe puting some doses on something - they are both weak selfheals.
Try to set ur trait as much as u can - to pierce teammates with healing and enemies with sleep. And again: be behind the team. When u get in front of team, u can switch trait to run away (at normal speed).
Try to be accurate, as much as you can!
Remember: This build needs you to focus on both: healing teammates, and dosing enemies!

Eye of Horus ulti is more flexible at helping - i pick it, but the other ulti is to consider.

13: incrasing speed seems always good, and the other talent removing stun is good just when enemies do alot stun.

when u reach lvl 16 and then 20, u can feel the power of this build. atacking fast and from far, and when you keep enemies dosed, your healing goes crazy.