Preferables

Just take it
Better, if you don't feel too safe.

Could be

Best alternative, if you feel that you don't have enough CC (you and your sup).
Hungry for kills? take it.
If you are scared about theirs CC and not about the damages? take it, another good option.

To take they to the dead with You (if you die sometime).

You ability less useful, but you can't be perfect, Deadly Bloom is good for casting to charge the tear and spam the Lizard effect.

Perfect synergism with your E ♥.

As hoobastank, the reason, the reason of playing Zyra ADC.

Nobody could run from you, try to cast immediately after E.

Marks

Don't touch anything, this is perfect. Play Video

Seals

Don't touch anything too, you have to resist vs that Ad. Play Video

Glyphs

If you are vs an AP HEAVY CASTER (even at early, as Annie) take Glyph of Magic Resist or Scaling (better not escalated).

Quints

If you want to start with Long sword you can take one or two quints of Life Steal, but not too much, remember that you need a lot of ad (because your standard ad is low).

Just focus on the farm, try to lasthit everytime. Play Video

Starting

Activate smart cast on Q and E

Change your interface settings, you would like to see more around You, You would be the focus, be thoughful.

Good way to use Your seeds, steal monsters where You can't see (perfect for taking buffs).

When you sup runs out of wards, and You are without trinket, ward tribush and riverbush with yours seeds (You can have 4 at the same time on the map).

Just want to thank You all so much (if you read this :( ). I'm so sorry about the format of this guide, i know that is ugly but is my first.
Try it, is powerful because of that powerful E, and is very funny.

STOP HATING, STOP BEING AN CLOSED MIND, IF YOU DON'T LIKE IT, GET OUT.

Oh, and i'm from Venezuela, the country with the craziest presidents of the entire world xD, by that my interface is in Spanish and i have a lot of errors at the post :( but you should get it, enjoy it, thanks.