Need some advice on new champs

So for 3 seasons, I've tried to adc. While I'm decent with Vayne and Varus, I find my lack of variety (in terms of skill using other champs), keeps me down and I end up losing lane a lot by being countered. So this year I switched to mid. I've been getting more positive results using Talon, Zed and Zyra. Zyra I have pretty much figured out, just need to tweak my items, which would be great to hear what goes good with her. As for Talon and Zed, I usually go something like 6/7/7 or 10/8/6 for example. Not that great. I've been checking out mobafire guides but nothing really seems to make these guys pop. I understand it has a lot to do with skill too but it feels like I'm losing a lot of damage as the opponents acquire armor items. So it would be great to hear what items really make those 3 champs stand out and some basics on how to make sure I don't fall behind easily.