A little about myself "Abscindo"...
This is my first guide and one I'll be working on regularly as Zagara is my go to powerhouse.
I'll apologize in advance, I'm not a writer, but the build is very effective.
I encourage criticism and I hope this helps some folks.
There that is enough... on with the show.

I'll start with... Zagara: Mother of the Brood is Thirsty for Flesh... is an excellent guide with the exception of a few changes which I will explain briefly below while still maintaining the emphasis on Lane Bullying from a distance.

The first and most important of the changes I choose to use Maw in most situations over the Nydus.
Maw Pros:
[*] Excellent escape tool.
[*] Excellent delay tactic if you just need a few extra seconds for your teammates to get on the scene.
[*] Can snag multiple enemies.
[*] Can break the momentum of an enemy lane push especially when they bunch up against your gates. combined with Kerrigan's grab can turn a bad situation in your favor.
[*] Gives you the opportunity to time and line up your baneling attack.
[*] Really drive home that if you're straggling you are not going to be getting away =p

The second change I have in play is the Giant Killer talent. While the hunter killers are useful I find that Giant Killer in tandem with envenomed spines gives you have more control and can allow you to more effectively direct your damage.

Patience is key with this build... really its key with this hero. If you jump into the fray you will die.

Push when the pushing is good and when its not keep up the pressure with your banelings but maintain your distance... You will die quickly in close quarters. (If you do get sucked in Maw is your out.)

Once you have 8 banelings you can take out mobs on the blackheart and mines maps with a single stream of these guys so they are a heavy asset for quickly acquiring skulls and coins on those maps even without backup... which should be there but we all know it usually isn't.

On the dragon Knight map I find Zagara quite useful in the middle lane to disrupt the acquisition of the dragon knight if your teams a bit of extra time to require the... you know.. pad things...

Creep everything if for no other reason that VISIBILITY! If you know where they are than you know where to be and when to be there.

I find Sgt. Hammers range to be incredibly annoying but effective... Enter... Zagara.