This is, in its current state only a build, but i will try to expand it, and make it an complete guide. If you want to learn how to play Poppy, this is the wrong place for you (for the time being). A great guide on how to get started is this one written by Belgarius.
I take great inspiration in the amazing Poppy player, Spamhappy (watch him he's crazy skilled). My primary point in this guide is currently to show why Cloth Armor is most often a better starting item than Regrowth Pendant.

spaaaaaaace

Pros + Tons of damage + Great damage reduction + Awesome tower-diving + Almost unbeatable 1v1 + Snowballs + Escape with Paragon of Demacia

space

space

Cons - Hard to farm - Not great versus magic damage dealers - Needs items - Can get shut down early-mid game

The runes in this build are pretty standard. Refer to any Poppy guide for greater amount of details.


Marks
Greater Mark of Desolation x9 These will break down any bruiser in top lane and armor penetration doesn't loose its power in the same way that pure AD runes do.
If you are having a really tough time last hitting, you might want to try using Greater Mark of Strenght for a couple of games.

Seals
Greater Seal of Armor x9 Having armor in the toplane is key, and every little bit counts. See starting items where i discuss the value of armor in top lane. THESE ARE NON NEGOTIABLE!

Glyphs
Greater Glyph of Magic Resist x9 These will help you survive agianst any magic damage that will come your way, since you will not be getting much from items the first parts of the game. They also help out a lot when getting ganked.

Quintessences
Greater Quintessence of Attack Damage x3 ads too your base damage ie. makes you even more hurtful and will help you last hit if you're not very skilled (takes practice with Poppy). I recommend Greater Quintessence of Attack Damage because it will give you a nice boost too your early game, and in the late game your Greater Mark of Desolation will really kick in.

Hardiness
Every little peace of armor counts!


Veteran's Scars
A little health is always a great thing.


Honor Guard
This is one nice buff. It will get you that little bit of an advantage, combine this with your huge armor stack, you'll be in great shape!


Juggernaut
The reduction of CC will help no matter how you look at it. You'll survive a lot of things. it also helps out great in team fights.

Section will be expanded

For summoner spells i recommend Exhaust and Ghost. The reason for this is that both can be used defensively and offensively.

Exhaust will take one person completly out of the fight, and slow them down. The slow will allow you to either catch up and deal damage, or run away to safety.

Ghost will boost your movement. This is all you need to know. You can either run from an opponent or you can catch up and stay on your target.

Other viable choices
There really aren't anyother summoner spells that will work as well as the before mentioned, but for sake of completing this guide i'll tell you why not.

Section will be expanded

I often see many people starting with Heroic Charge, but as poppy you don't want too have a level 1 engagement. You are far better of waiting until level 2 when you have the defense from Paragon of Demacia and the offense of Devastating Blow or Heroic Charge.
Devastating Blow Bread and Butter. Use it whenever your opponent dares come near you. This skill combined with Sheen is certian too hurt anyone. This is your second priority level it as often as possible.

Paragon of Demacia Defensive & Offensive Boost. This skill will make sure you can run out or into an engagement PLUS it will boost your defense and offense. This skill is a sort of "one point wonder". Just one point is enough to make an gigantic impact. If you should max this second or last is situational, but in general it should be your third priority.

Heroic Charge Stun & Damage This skill is great. It deals huge damage, but only if you hit a wall. If your agianst an player who knows to stay away from walls this skill doesn't have an great impact. If they don't respect it's stun and damage take it after maxing Devastating Blow but in general your opponent will learn to stay away from the walls and then it's better to max Paragon of Demacia.

Diplomatic Immunity You Can't Touch Me. This skill is the one that will buy you time. It Has so many different uses and is one of the greatest skills in the game. It will let you run around between everyone. You will get a damage bonus to your target, and the team can't help them out. The price you pay is a huge cooldown. Let me tell you what you do with this skill.

Your starting items will vary depending on your opponent. Generally you need to know witch type of damage your opponent does.

vs. AD-Bruisers

5x

Most solo-top champions are AD-bruisers, meaning they do physical damage and will have high surviveability. Typical example is Riven or Gangplank. They do heavy physical damage and have large health pools and have abilities that let them survive in duels.

When you are agianst AD-bruisers you want to start with Cloth Armor and 5x Health Potion. Why, you ask? i often see people going Regrowth Pendant no matter the opponent, and the thought process is ok, Regrowth Pendant is a great item that will let you recover from almost any exchange, but why would you want to recover when you can avoid damage in the first place? If you start by taking Cloth Armor with Paragon of Demacia you will have 73.7 armor. This equals a physical damage reduction of 42.4 %. AT LEVEL 1!
That is awesome!
Try going up agianst Riven. Oh, you used Broken Wings and did 203.4 (max) damage at level 1... Well, after my armor you only did 117.1 damage. In the meantime I hit you, say three times... That's 56.3 damage per hit, equals 168.9 damage... Now take a level two engagement when you got Devastating Blow... Now you reduce her damage by 43.7 %, but one of your hits does 119.675 damage while the two others do 59.675 damage. Now you're a beast doing great damage plus negating almost everything the throw at you.


vs. Anything else



Basically, when your playing agianst anyone who is not physical damage based you need to take Regrowth Pendant. The best thing you can do is to rush your Philosopher's Stone and make sure you that you don't get killed. Hang back and get what last hits you can and recover from whatever health loss you will get. Try to stay at your tower, last hitting and wait for them to make a mistake. Call for ganks and build an advantage slowly and surely. If you're getting completly screwed you might want to by Hearth of Gold, or something to counter the type of damage they're dealing. An early Null-Magic Mantle might be a good idea, because it will build inte a nice pair of Mercury's Treads.

Section will be expanded

First Trip Back
Philosopher's Stone

On your first trip back, you should have gotten enough gold for your Philosopher's Stone. This item is a must. It will sustain you, with it's HP regen and Mana Regen, and the extra gold will help you get your core items faster AND let you push any advantage you have gotten.

Get These Quickly!
or

Your next item, your boots, is dependent on who your opponent is. In general I recommend Ninja Tabi agianst AD-bruisers, too make them even more ineffective. However if your opponent has a lot of CC or is not an AD-champion you should get Mercury's Treads.

Why not Berserker's Greaves?
Let's start by seeing what bonuses Berserker's Greaves gives you. It will give you 25 % attack speed and increased moving speed. the increase in moving speed will be the same if you pick Ninja Tabi or Mercury's Treads, but Ninja Tabi will reduce incomming damage by 10 % and give you some armor, for only 550 gold, while it would cost you 970 to get yourself Berserker's Greaves. If you're agianst anyone who deals magic damage you need to make sure you don't die and magic resistance is the way to survive in such an case, therefor: Mercury's Treads

Now, Your Blue Sword!


Now the fun items are comming. Now your next item is what will make you deal damage like a mad little yordle! Sheen. This item is wonderful and pretty much any kind of Poppy player agrees that this item is core. It will boost your damage with AP, synergizes with Devastating Blow and gives you some much needed mana.

Towards the Trinity!


Next you need to continue building your Trinity Force i usually go for Phage at this point. It will give you some health, damage and that oh so delicious slow.

Trinity Force, My Dear Friend


To finish Trinity Force you might want to by Zeal but i usually have the money for Trinity Force before i need to go back agian.

After Trinity Force you will want situational items. Look at the game your playing. Still in the lanes and your stronger than your opponent? Go for Hextech Gunblade. Getting stomped by AD? Get Frozen Hearth. Need some bigger damage? Infinity Edge is your answer. Dominating your game and want to catch people? Phanthom Dancer all the way! The list goes on. For now, look up some of the other guides for more details.

I would really enjoy some CONSTRUCTIVE critisism. I don't apreciate comments writting "you're wrong madafacka EAT MY SAHBFSADUGBVFIPASGFVBA" if that's your opinion tell my why and i will expand that section so i can make this guide better. This is my first guide and it is still under construction, but i thought it was good enough now to go public as a sort of BETA-test ;)

Hugs & kisses
TraRice