Well hello there. my name is mees from gamingdutchfans!
Here is a Quick revieuw About APC Singed!

Pros? CONS

Tank. Focused when op (like teemo or kat.)
High damage. No health gen.
Gas tank. A quick jungle for 100 money is NOT possible iwhtout losing 300Hp.
just epic. He makes you think of a certain man. Hint:WW2
Quick

Runes. i take pure ap glyphs and quints. with armor runes. sadly im too poor to afford magic pen runes. if you have the money get magic pen marks.

Ap ap ap. Doing 300DMG/second with oyur Q
and your E doing a WHOPPING 1000 Dmg!
While Having +3000HP thanks to oyur passive!

Masteries. just the ap offensive tree with a little more defense than normal.

E so you can reach them or stop from running.
W for slowing.
and if u dont with your build. always keep your Q on.

Spells. Flash+Exaust is a rare combination.
But very effective lets say. You have no mana and are level 6.
you have near to full hp and the enemy 300HP not enough for ingite.
Use exaust as the only way to slow and flash to him and kill it with a Higher chance of killing the enemy!

NO. just NO.

NO JUST NO NONONONONOOOOOOOOOO

E and Q lovely
you have 500HP and enemy 1000Hp
Its You vs garen(fed)
He chases you. use Q to damage him.
when he has low HP or gets close.
use W for slowing and at last E for massive damage.

Use Q!
No Q? no minions!
walk in a heap of minions and put your q on and walk in circles!
Its very easy to farm heaps of 20+ minions.