I need to start archiving my posts. I wrote a pretty comprehencive TvZ guide on here once and even master level players said it helped them out. I will try recollect my thoughts on the matter...

A Guide of TvZ from a Diamond Terran Perspective

There are a few fundamentals you'll have to get used too for TvZ that are entirely different from the other matchups.

This is just going to be a bunch of pointers / my thoughts on things with some subheadings, I could be a moron. Don't listen to me unless you find some internal logical consistency with what I have to say.

Turrets (this knowledge improved my macro quite a bit)

With turrets there is a golden rule, and that is, that if one turret won't scare off his mutas, then neither will 3. There is a critical mass where he will engage turrets, and a mass where he will not, the number you place down does not seem to affect this very greatly. If your going to build 4 of the things, put them all over for good area coverage so he cannot camp your base in a “sweet spot” don't expect that by putting 4 near your workers you are safe. Make sure there is one near your unit producing structures. Last thing you need after a baneling bust is for every marine and tank to die when it is produced all alone.

But the most important thing about Turrets, (and I am all for getting a fast engi and getting those deadly deadly marine upgrades) is that you should not build any until after 9 minutes. Mutas are not a threat until 10:30 – 11:00 minutes typically, and dropping them too fast is wasting mining time and resources that could be supply depots and infrastructure, and most importantly, the expenditure weakens you in the early game needlessly. Also, if you've been baneling busted, check if he even has a Lair, battling the deadly Zerg all-in can be hard, no point building turrets that don't shoot at anythign he has.

Production

If your reading this you are likely a Terran player who has lost thousands and thousands of Marines to Infestors, Banelings, and Speedling surrounds. We all want to turn into MarineKingPrime and be able to walk into battles against these units and best them, but even he tends to only pull out just enough units to keep his push alive or protect his tanks. So if the best of the best is still losing units in this fashion, what hope do we have? None. But the first step is to be cool with that.

Take the number of Rax you think is reasonable, then double that number. Everytime you have a mineral surplus, add rax. Make chokes with them, put them at ramps, put them wherever they fit, but be sure to make a LOT of them. No matter what you do you will lose a lot of Marines. Keep them alive and make them cost effective sure, but in the end, they will fall, and they need to be replaced.

If you don't use hotkeys, (thats bad but whatever) at least make sure you have all your rax on a key. I have a new keyboard and my A button is already faded.

Engagements

When you move out into the map, you may have map control, but you probably dont have creep vision. For all you know he is considering attacking, he just morphed all his lings to banes, and all his larva to lings and roaches. It sucks but sometimes you move out with everything and it just gets stomped on. I wish I had good advice for this, try baby your army, and move it in 2-3 smaller groups that are close to each other to prevent getting walked over, but the fact of the matter is, when two armies catch each other off guard, Zerg wins. Period.

Seige at the edge of the creep, seige when you get nervous, seige if a single unit has spotted your army. But once you seige, start crawling, because something in a Zerg players brain, they are afraid of an army walking out on the map, but once it has seiged, and unseiged, they tend to 1A you hard.. We cant start crawling with tanks (leap-frogging) from our doorstep to theirs otherwise they would just run about the map killing expansions and tearing us apart, so for a portion of the travel time, you will have to be ballsy and just waltz at him. Hopefully your army is intimidating enough. Most Zergs will actually start producing units, and move their existing units to flanking positions. This is good because it buys us time. Being flanked sucks, but not as much as being caught unseiged.

Rally Marines somewhere just outside of the vision of the battle while your fighting. You don't want them to stream in if everything goes wrong, but having a group of 10-20 marines ready to join the fight grouped up and strong is very useful.

Pushing out without Stim makes Baby Jesus cry. Stimming without Medivacs makes me cry. Sadly it's hard to keep up with Zergs swarming power while still teching to medivacs, but it is absolutely necessary if you want to win. You can do a push with combat shields and 2 tanks, or +1 and stim or something, but if you ever reach a point in the game where it is reasonable that you COULD have stim done, then you not only SHOULD but you should not leave your base without it from that theoretical point onwards.

When a Zerg tries to snipe tanks with mutas, and you are expecting ling/bling to come in from the opposite side of your tanks. Stim and fight the mutas. Either the mutaswill run, leaving you behind the tanks in a good position against banes, or, you'll kill the more expensive part of his army and lose your army when he army-trades. He gets to choose which, but at least you get the luxury of knowing one of the two more favorable engagement outcomes is guaranteed.

Attack new bases. If you want to kill tech, do it with drops, but by the time your comfortable being out on the map, the best place to hit him is his third and fourth base. Deny him income, do not deny him tech, he can make a lair, spawning pool, and roach warren all at once at another base and survive. His infastructure is not like Terrans, you don't need several buildings per tech path, you need mining bases and income. Also, if a Zerg has no mining bases, expect he has a lot of minerals banked (they just do) they can continue to expand from a position you'd expect a Terran was broke. They can also produce a few desperate last ditch armies. Don't celebrate before the victory. Zerg is always dangerous.

I didn't cover nearly half of what I wanted too but I am lazy.