ZvP ling drop opener :
double extractor trick
16 expand (the 16 expand allows you to get your hatch up before the Protoss can pylon block it on most maps)
@125 gas pull workers off gas
@2:40 get evo chamber + 3rd hatch
@100% ling speed get a dropperlord
Have 16 drones on main, 8 on natural and 2 queens + start 1 more when the 3rd finishes
If you decide to transition put back on gas so you can get +1 and bane nest, you can pick the order depending on what you scout (bane nest first is safer against adepts).
Send your lings to your opponents base just before ling speed finishes
bane + an upgrade (+1 melee helps a lot against adepts and can help you sto snipe their 3rd base, but +1 range will make be better for your hydra transition) -> hydra -> lurker -> brood or viper depending on if charge archon or tempest is my overall game plan
If you float minerals just make some queens
For hydra you need at least 4 gas and for lurker you ideally need 6 and for brood and other hive tech 8 you will usually need 8
(bare in mind this is just general plan and there many be situations where you want to go do these things of less or more gas or even go an entirely different tech route)
The opening ling drop can be used to go allin or you can go just 8 lings to kill probes and scout. This sets you up for a good mid game since it can knock the Protoss off their game a bit and it makes it very easy for you to spot their tech and react to it.
Also feel free to ask any questions or explain to my why this style of playing ZvP is stupid