Cassiopia is a very powerful mage with long attack range,with three AOE skills,you can harass your rival and do farming at the same time. The hard part is Q your rival properly,this might need some imagination,especially when you're lack of Mana in the beginning.

Very aggressive choice,as a mage,i'd like to suppress my rival at the first place.

My general mage mastery,i use it for Cassiopia，Oriana and LeBlanc,full attack and certain cruising power.

I'm not sure this need any pattern,sometimes i'll start W at level 5 or 7 when other lanes can't spare hands to Gank. But in some cases,if you deal with someone with high move speed Evelynn or smokescreen ability Akali ,open your W at level 3 to expand your attack range,if you can't save Mana,exchange some blood back. But Noxious Blast is always the highest priority. - A newbie's thinking

Flash: This is a must for escape and good position to Gank.
Teleport: I don't like to lose turret,some sort of obsession.

Boots + 2x Health Potion + 2x Mana Potion.As you know,after the 6.20th update,the Boots of Speed reduce 25,now it costs 325,so i think this is a good start.

As the APC, you're going to want to do some damage and be alive. Haunting Guise provides both for Cassiopia.

There are many APCs use Athene's unholy grail as the first key weapon, LeBlanc is one of them.

Push the lane and harass your enemy,force them back home,then depends on the side lane's situation,you can choose to give a hand or go jungling. Cassiopia can make money quickly,so help your support to buy some sight ward for the team,mates will love you. Thanks! : )