First rush to Ryalais, it gives you some Tankines, AP and the effekt is Godlike for Singed. For the 2th Item, pick a Tank Item like Deadman´s Plate against AD or Banshee´s Veil against AP. The effekt from Deadmans Plate is very usefull for Singed. ZZ´ Rot is a really good choice too because it gives you movement speed when you are nearly Towers, it helps you Pushing with the Void Minions and it give you Armor and Magic Resistence. For Boots Choose against your Laner oder if you are Fed go with something offensive like Magic Pen Boots. For last Items are items Like Ludens Echo or Abyssal Scepter good and for Tankiness helps Warmogs and Randuin´s Omen much.