The quickest way to level up your conjuration is by getting the spell http://en.uesp.net/wiki/Skyrim:Bound_Weapon, starting a fight (http://en.uesp.net/wiki/Skyrim:Mudcrab are the best opponents for this), casting the spell (one or two hands), when hearing the sound which comes right after you've launched the spell, cancel (so you don't have to wait for the weapons to appear), repeat.
http://en.uesp.net/wiki/Skyrim:Conjuration#Gaining_Skill_XP
With Bound Sword there′s no need to be cheesy, it gives huge amounts of xp everytime it′s summoned in battle, just dual wield those babies. Power attacking with bound weapons is really cheap, which is nice for everyone but for mages in general, and they′re basic Daedric swords, not bad at all. Unless you′re powergaming with smithing and crafting, the difference in the amount of stamina you use to power attack often makes up for the lack of sharpening and enchanting. You can poison them as well.