Poppy's laning phase is generally quite bad. During this time of the game you most likely will want to farm under tower and play everything safe. A lot of times people will be tempted to tower dive you, when that happens you simply exhaust them and stun them against the tower. I wouldn't reccomend running off after you stun because your q does do a lot of damage. Also, ask for some early banks. Exhaust is great for setting them up, and if you can land a stun with heroic charge, even better! If you really are getting wrecked and can not farm whatsoever, do not be scared to buy an ancient coin or some sort of gold income item.

Generally, the idea with Poppy is that you ult a support and dive the ad carry. Personally, I like to ult the ad carry and dive the ad carry. If you have built the above items with the masteries and runes, you should be very resiliant to the damage an ad carry can throw at you. Also, her passive should help win her a fight with an adc. My problem with ulting supports is lots of times they have massive amounts of CC and can simply stall your ult away. Situations in which I would not recommend ulting a support would be with Janna, Leona, Nami, or Lulu. Then again ulting an adc might not be the best bet if it's someone who can pass through all your armor like a Vayne.

One fantastic person to synergise with Poppy would be Jarvan IV, they can both dive the back or front line together and assuming that J4 has built slightly tanky you can both deal lots of damage while recieving quite a bit yourself while your major damage dealers stay safe from the back.

Thank you for taking the time to read my guide and I hope I have inspired you to at least try one of my favorite champions, Poppy.