I main Vlad. (Well that may be an overstatement, I kind of fell into him when Sona got gutted, and now Miss Fortune of all things is possibly overtaking Vlad as what I'd call my main) If it helps to say, here's what I do against most of them:
I almost always start with an amplifying tome and a potion, simply because more AP means more healing. I also bring Spellvamp runes. They're expensive, sure, but having half a hextech gunblade should do wonders at all points in the game.
Play really aggressive against Darius and Fiora in the first level or two, (poke whenever you can) but shift into being more passive once they get all their skills. Your goal then becomes to avoid confrontation against all four of them. Beware Darius' pull. Keep track of Fiora's vital markings; If you see the marking thing pointing towards Fiora, keep your distance until it goes away. If the marking points towards your tower, you should be fine. Of course, position to avoid her dashing in to hit your vitals if it ever points somewhere in between.
On your first recall, rush Ionian's. This is less important for Fiora and more important for the rest. If you're fighting a Darius or if Ionian's isn't enough, don't be afraid to rush Alacrity as well. Movement speed, assuming they don't also rush boots, will give you an enormous edge against these four, especially Darius and Garen. Darius can be extremely oppressive if he has an advantage. His pull can become inescapable. Movement speed lets you bait them out much easier and makes disengaging against him (and preventing engages) possible. Against Garen, he simply can't get to you, and if he runs at you, you can still get away before he closes the distance. Against Fiora, it's a bit trickier, but as long as you don't let her at your vitals, you should be able to outpoke her and deny her all-ins. Against Riven, you can walk away from her when she tries dashing onto you and punish her for it with pokes.
If you do this all well enough, you should be able to deny farm to all of them except Fiora when you have a vital mark pointing her way and Darius because Darius. When that happens, always be careful of ganks.
Once you get spellvamp, (sometimes even if you haven't finished WoTA) I also highly recommend building a Rylai's. It gives you a lot of cc and makes you excellent at kiting. If you're far ahead, it makes it very hard to get away from you.