Welcome to all. Here's my first guide. This guide will be based on one of my favorite champs, Singed , The mad chemist. Singed is an AP/tank champ who needs a lot of swiftness to be well played. He has a good engage and can easily chase/seperate people. His mouvement speed will guarantee him an easy escape and chase even if enemy team has escape spells.

As masteries, I take 1/21/8 because Singed has to have some armor/Rm since he has to intitiate at teamfights. You'll have to take Vigor to secure your earlygame. You'll also need Initiator and Swiftness to increase your movement speed. These masteries give you enough speed to survive early game.

Marks: Armor to handle the top against bruisers: Irelia / Udyr/ Talon / Riven / Olaf
Seals: Regen Hp. Will help a lot with your ulti activated
Glyphs: Magic resist. To handle the toplane against: Vladimir/ Swain/ Gragas / Mordekaiser...
Glyphs: Movement Speed: Great boost with your items and Ulti/Ghost

Ghost: The best summoner spell for Singed. It gives a great boost. You'll easily chase/escape. Don't be afraid to use it with your ultimate. It's doesn't have long CD. So don't hesitate.
Exhaust: It's a very spell against ad champs and it can slow so chasing/escaping will be an easy job for you.
Cleanse: Singed is a very mobile tank but he's too susceptible to movement cc (slows-stuns) so as said before, you'll have to pick cleans to counter that.
Teleport: It's a really good summoner spell. You can tp on turret to farm quickly or even tp on wards to gank bot/mid lane.
Flash: I don't that it's good to take flash with singed but some guys will prefer too.
Revive: Just don't take this summoner spell. It's better to stay alive than to die.

1- Empowered Bulwark: It's singed's passive. It turns every 100 mana in to 25 health. Great passive.
2- Poison Trail: This is Singed's main spell. It's his mainly source of damage. It deals damage (DoT to the one behind you)to the one's who are chasing you. Will certainly disuade some people to chase you or an allie. Care this spell is a mana swallower.
3- Mega Adhesive : One of his most underrated moves! Skillshot slow which helps you land your flip. It'll be very helpful when maxed at lvl 5. Notice: Don't hesitate to use this spell to get an assisst. Even if it doesn't deal damage you can take assissts if you hit an enemy with the Mega adhesive.
4- Fling : Here's the spell which will help you to initiate teamfights. You'll have to fling the enemy Ap/Ad carry (the most fed) to your team.
5- Insanity Potion : Singed drinks a potion that gives buff him. It gives him Ability Power, Armor, Magic Resist, Movement Speed, Health Regeneration, Mana Regeneration and reducing CC Effects boosts. You will use it with Ghost to escape/chase easily or to heal

Singed's build is totally based on the enemy team (how many AP vs how many AD). Singed's stuff is easy to get if you farm well and get kills/assissts.
Against AD enemies as Irelia]/ad Sion / Talon:
You'll start with Regrowth Pendant and a heal potion. Because ad enemies start making damge since the first levels so you'll have to get a good regen to face them and get close to them until you have your adhesive and be ready for the jungler's gank. At your first back you'll take Philosopher's Stone and Boots of Swiftness. You'll be more speed and the mana regen will help you stay long time in lane. Philosopher's Stone will also give you a gold boost.
Then after that get sure to get Sunfire Aegis and Banshee's Veil.
The rest of the build depends on your enemy team.
Against mainly ad:
You'll take Thornmail, Frozen Heart and Guardian Angel. THis build will assure singed armor and health with the mana that Frozen heart gives.
Against mainly ap:
You'll pick Force of Nature, Abyssal Mask and Rylai's Crystal Scepter . This build will give you enough magic resist.

Explications

:
Rylai's Crystal Scepter on Singed is good if your team don't deal enough DPS. Plus, It'll give you Health and will slow enemies that chase you, since you're activating your poison.
Frozen Heart: Provides Armor and mana which is changed to HP thanks to Singed's passive.
Sunfire Aegis: Gives Armor and health. Plus, synergizes with your poison.
[Banshee's veil: Blocks Slows, Stuns, Silences and imobilisations.
Philosopher's Stone: Boosts your gold in early game. You can up this item to Shurelya's Battlesong for Speed boost or Eleisa's Miracle for Tenacity.

FARMING, That's the most important thing to do in the first 20 minutes. The ideal creeps are 160 creep/20 minutes but you can do less. Farming as Singed is very easy. You'll first have to last hit until the lvl 5. From that you can easily use your poison trail on mininos they will fall quickly low health and you'll just last hit. Harassing is also a good technique to stop the enemy from farming up. So don't hesitate to do that. But care Singed can easily fall low mana. So don't waste it. With this stuff I think it's hard to kill unless you're playing against a bad solotop. You'll have to wait for your Jungler's help. I rarely take kills with singed, I prefere to let them to the carries or to the jungler if he does good damages.Notice: in teamfights don't forget to use your Mega Adhesive to get assissts.

You have to avoid all the CC's champs.
Ashe
Nunu & Willump
Sion
Irelia
Sona
Taric
Yorick
Warwick
I still think that If you farmed well and get the items, summoner spells that I Advised you, these champions won't get you.

That was all. Thank your for reading and I hope that this guide helped you. I'll update this guide if there's any change on Singed or even the items that he gets. Like this guide or post a comment there's something that I forgot or something to correct.
Thanks to Jhoijhoi. Her guide helped me a lot.