If You Disagree Please List Reasons

Lets begin With understanding the role of singed. singed can be played as a 2nd tank or a 1st tank during ranked games. The job of a tank is to start fights and protect your carry.
your throw as singed is a go initiator and a good way to get the enemy off your carry or any other person in trouble so save that skill for situation such as those. Positioning is everything with singed.

Cons
1. Singed has a Poor Mana Pool Early Game.
This can be solved by saving your mana for situation such as, kill a few creeps off with your position and then going back to last hitting(for those who don't know what last hitting is, its when your hit the enemy one time when there at low life and they die.

2. Can be countered by ranged early game.
This Can simple be avoided by going in and out of the brush in your lane or simple letting the minions push to your turret and constantly last it to make sure you take minimal damage.

Pros
1. Super Tanky
Mid/late game your becoming super tanky and your ult eve make your more tanky
2. You become every class.
Your Ult make you Hybrid of AP/AD

Flash
Teleports your champion to target nearby location. Flash throws Are Great ways to start a fight and escape from one.
Ghost
Your champion ignores unit collision and moves 32% faster for 14 seconds.
use this skill to chase enemy down with poison or to throw them back into your team
Other Option
Cleanse
Removes all stuns, slows, taunts, fears, snares, sleeps, silences, blinds and immobilizers and reduces the duration of newer applied ones by 65% for 3 seconds. I use this summoner skill if Other Team has a rammus or a gallio so i can instantly stop them. This Skill Replaces Flash

Your Summoner Skils Are for helping to chase/escape from enemies

Jungleing isnt a priority on singed but its good to know that you can.

You Lane till your lvl 3/4(depending on your lane partner).
make sure you have at-least lvl 2 poison and 1 or 2 health pots.
start at blue buff and work your way around just like you normally would if your jungle.
You can also use this to counter jungle your opponent by going into your enemy jungle
and killing the creeps(leave 1 monster alive so the creep won't re-spawn


Just a Basic outlook of which path you could take

Last hit Minions and use your poison only to control the movement on creeps.

Greater Mark of Resilience x9
+0.91 armor More Armor makes it harder to be killed.
Greater Seal of Evasion x9
+0.75% dodge Dodging a attack is alot better then tanking one, this also helps your nimbleness mastery.
Glyph of Shielding x9
+0.12 magic resist per level (2.16 at champion level 18) AP damage isn't really a concern in the early laning phase. The per level runes should even out before you really need magic resist.
Greater Quintessence of Swiftness x3
+1.5% movement speed Move faster = more grabs, this combined with your slow makes it incredibly hard to escape from.

If you buy one doran item on singed your bad.

im only gonna cover important items

Item Explanations:
Sapphire Crystal
200 Mana. more mana and more health(because of your passive) enough said.
Catalyst the Protector
290 Health, 325 Mana. Passive: Restores 300 Health and 250 Mana upon leveling up. Gives a perfect balance of Health and Mana, and gives you Health and Mana when you level up(Which you will do VERY often early game)
Mercury's Treads
25 Magic Resist. UNIQUE Passive: Enhanced Movement 2 and reduces the duration of stuns, slows, taunts, fears, snares, sleeps, and immobilizes by 35%.
Reduces CC effect, if the other team has no CC just get boots of swiftness.
Rod of Ages
80 Ability Power, 630 Health, 725 Mana. Passive: Your Champion gains 18 Health, 20 Mana, and 2 Ability Power every 1 min. Bonuses cap at +180 Health, +200 Mana and +20 Ability Power. more health/mana and some ap, which makes your harder to kill and your poison/fling does some more damage now.

Banshee's Veil
375 Health, 375 Mana, 50 Magic Resist. UNIQUE Passive: Blocks one negative spell every 30 seconds. Straight-up stops one spell every 30 seconds, entirely negating its damage and crowd control effects.

Thornmail
100 Armor. UNIQUE Passive: On being hit by standard attacks, returns 30% of damage taken as magic damage.
counters dps champions by Reflect damage back at them.

Side note:
If the other team is more AP then AD you could get a force of nature instead of thormail.

1- Spam your Adhesive often, use it to slow enemy and help your ally escape from a chase.

2- Fling your opponent off/into your ally.(depends on situation)

3- When being chase turn your poison trail to damage them causing the other team to stop chasing or die.

4- Position is everything with singed so make sure your always setting up for the next throw.

5- If a enemy is close to your turret throw them into it.