I've is a defensive school so play to your strengths. Go with good gear that has resist, it all ads up but not Jade. Dragoons robe and boots with the Malistair hat is a good starting place. I haven't looked into the new level 140 gear yet so may be something better but I do know the new ice amulet is definitely worth it.
Preferably have a pet with spell proof and the defy brace jewel socketed. The last it's good to to have wards in the last 4 slots covering the most threatening schools. Since the update it's hard to say what they are but definitely fire and ice.
Wand, ring, amulet and deck are your preference. Any circle sockets should be ice pierce.
As far as playing goes blades are your friend. If your opponent shields, frostbite. Pack stun blocks. Pack strike. Pack one dispel to every school for when they are in strike and a couple set shields to every school. Pack bubnles, lots of them. I've has the best bubble of all the school's so take advantage of it and fight for control.
That should be enough to get you started. The rest is up to you to figure out what works best for you with practice
Wizard.