Pick him against low to mid range champions with low mobility and whose method of CSing stops their movement, like 
Pay attention to your own minion waves HP.
Whenever they stop moving to throw an auto or spell at a creep, throw Q for a bomb with a high chance of hitting.
VesperNadal2 votesAlso get some flat AD marks on Zilean. His ability to last hit under tower (from my experience) is really poor when under his turret. The usual "2 turret shots and 1 auto attack" trick doesn't work for him.
HolyCrapItsMe1 votesThen do what you do on ranged minions, auto, double tower shot, auto, I think there are better runes to be taken on him than AD.
TBakes1 votesYeah, I have found this to be the case as well. Once you get mana constraints under control you can use bombs to wave clear quicker, but early game it does not work like other champs.
Hasztalan21 votesOr just play a better champ.
IsmokeOregano3 voteszilean is highly underestimated. Especially as a non-support, hes literally unkillable with his ult and a full AP zilean dmg is insane. Plus the fact he has a stun and a permanent speed buff to self or nasus-strength slow to enemies if he builds a little CDR. I think you need to try more than the FotM champs before coming onto the help section of the boards and trash talking someone is is trying to be helpful
Hasztalan21 voteszilean is highly underestimated. Especially as a non-support, hes literally unkillable with his ult and a full AP zilean dmg is insane. Plus the fact he has a stun and a permanent speed buff to self or nasus-strength slow to enemies if he builds a little CDR. I think you need to try more than the FotM champs before coming onto the help section of the boards and trash talking someone is is trying to be helpful
You are talking to someone who plays shits like zyra jungle in d2 range .
And no zilean is trash. All he can do is sit on lane. 0 obejctive control, bad poke due to range and need another cc first to be able hit his bombs. Can't roam. REally suspectible for early ganks, easy to bait out etcetc. No. Overall he is really underwhelming and there are shitton champs who offers a lot more than him.
JustJayson1 votesI like zilean as well, only issue is at higher elo you will find it very difficult to land bombs without using slow initially. His combo is way too mana hungry pretty much forcing you to use 2 item slots for mana. If there was an ability put in such as refund certain amount of mana on stun or make his W no cost then I would go back to playing him more.
I know there is a rework of his passive in pbe at the moment, but that doesn't really help a solo lane zilean
