Lich Bane- You're ahead and wanna kill people even faster
Zhonya's- Against a lotta burst and a good grab if you steal a fiddle or swain ulti
Nashor's tooth- you wanna spam abilities and attack with your passive even faster
Rabadons- 5th or 6th item. Just a good thing to finish with
Demonic Embrace- I rarely pick this up but it's good against really tanky comps
Cosmic Drive- Love this item purely becuase it buff a bit of everything. I'd grab this 4th-ish
Void staff- they building MR
Morellonomicon- They heal too much like Warwick
Banshee's- they have too much CC to play the game

Always get bot side leash, your first clear is terrible.

Blue Buff start- Take blue, make sure you use your second E to interupt it's attacks and save some health. Youre gonna wanna pull the monster a bit to help yourself so go into practice tool and test it out until you can do it well. Go Gromp after, smite it early if you have to but doubt you will then go wolves. After that you go for an early gank and scuttle or if nothings pushed in then just go red.

Red Buff Start- Use E to intterupt it's attacks when you can, pull it around and save smite. You can go krugs and raptors for an early clear but it's risky so I like to go raptors after then clear blue side just in time for scuttle. Save your smite for gromp with this route and if you're not experienced then skip raptors.