Warwick's strength comes from his incredible sustain and durability in both the lane and jungle with his Eternal Thirst and Hungering Strike along with his ability to support his team with Hunter's Call and lockdown high priority targets with Infinite Duress. However, he lacks hard burst and is reliant on his teammates to follow up with him.
Due to the sustain granted by Eternal Thirst and Hungering Strike, Warwick can easily remain at full health in the jungle, allowing him to take many jungle routes and making him difficult to counter-jungle.
In the jungle, Warwick benefits most from armor and attack speed runes as it increases the effectiveness of Eternal Thirst while making it easier to kill jungler monsters.
His lack of AoE makes his clear time somewhat slow, which aggressive junglers can take advantage of.
Hunter's Call can help a lot when pushing a lane since it will increase the attack speed of both you and your allies and also grants Warwick and his team strong objective control regardless of build.
Hunter's Call can grant assists even if you are not close to the enemy champion, or even if you did not damage him yourself, so long as your ally had the buff active <15 seconds before making the kill.
Turn Blood Scent off to fool weakened enemies into thinking that you are not nearby, but don't forget to turn it on again later.
Warwick excels at hunting down fleeing or weakened enemy champions after teamfights. At max level, Blood Scent reveals the location of enemy champs with less than 50% health from great distances and gives him a large boost in speed for chasing, it also reveals their locations for all friendly champs, making escapes very difficult and preventing brush jukes.
Once Warwick hits level 6, his ganking ability spikes as his Infinite Duress has decent range and its CC is inescapable without an interrupt.
Warwick is also very useful in killing his pursuers. While running, cast Infinite Duress to regain most of the health you have lost, then spam the rest of your skills. This should shut down your pursuer's hope in killing you.
Take care when initiating a teamfight with Infinite Duress, as the enemy team will likely focus you quickly.
To maximize your ganking pressure you should try to force enemies to use their escape abilities such as Flash or Ghost before casting Infinite Duress.
When ganking, try saving Infinite Duress for later in the fight when enemies are trying to run away. This way you have a higher chance of getting a kill, however it is sometimes better to use Infinite Duress to suppress your target until your team catches up to them.
Only initiate the fight when your team can focus down an opponent to ensure they won't escape.
When choosing a target for Infinite Duress, be careful of targets who have spell-blocking abilities or Banshee's Veil, as it will completely negate the suppression on your ultimate.
Casting Infinite Duress on the enemy carry is the priority for Warwick in any team fight. The cooldown on the skill is relatively short, so don't be afraid to use it if you think it will grant your team a kill.
Due to the high damage and heal on Hungering Strike, Warwick works very well if you give him lots of resistance combined with spell penetration. While building him lots of on-hit effect effects like Wit's End and Nashor's Tooth is attractive, you risk making him a walking ultimate who will die very easily.
Morellonomicon is also an effective item on Warwick, giving him Ability Power, Mana Regen and Cooldown Reduction as well as synergizing with blood scent, preventing him opponent from meaningfully escaping with lifesteal.
Blade of the Ruined King has a great synergy with his ultimate, but due to its high price and as most players choose to build tanky before going for damage, it is recommended that it should be bought as a fourth or maybe fifth item.
Ravenous Hydra while lacking the percent damage on Blade of the Ruined King, has higher AD and thus scaling with Infinite Duress. It also procs the passive 5 times allowing you to deal a good deal of AoE damage if enemies are clustered around your target and helps him clear waves and camps much faster.
Remember that Infinite Duress cannot critically strike and does magic damage.
Building some survivability is crucial for Warwick since he has no innate defense mechanisms as a melee champion.
By building him tankier, Warwick becomes incredibly hard to kill due to high healing while still being able to put out hefty damage on enemies without having to fear sudden death. This will also maximize the effectiveness of any proc items you get by allowing him to stay in the fray for longer.
Warwick's lack of any multiple-target or AoE damage means he may miss out on assists during a team fight. Statikk Shiv ensures Warwick does some damage to nearby enemies when attacking, allowing for assist credit. Buffing friendly champions with Hunter's Call will also provide assist credit.
Warwick has the essential quality of any fighter, which is being both tanky and damage-capable. Therefore, a mix of items across tankiness, damage, and utility will maximize late game capacity on him.
Jungling order: Blue Golem (smite) → Wolves → Wraiths → Red Lizard (smite) → Small Golems → (Fountain / Gank) → Wolves → Wraiths → Small Golems → Wolves → Blue Golem → Wraiths → Red Lizard → (Gank) → Fountain at lv 7 → Dragon (assumes having Madred's Razors)
Note: Another set of starting items could be Cloth Armor, 2 × Health Potion, Sight Ward. The ward is almost always used to ward your own Blue Golem or Dragon, so if an enemy jungler attempts to take it, you can set up a gank. Alternatively, you can place the ward at enemy Blue/Red to try to gank the enemy champion trying to obtain the buff. Use Hunters Call after the 2nd attack in order to gain the most healing efficiency with Eternal Thirst.