The trick to Arcane is maximizing uptime on your burn phase. I do something a little bit different than the standard 'burn/regen/conserve' rotation. I use flame orb as a mana regeneration tool to give me another burn phase after my first burn phase.
Basically on a fight:
2 seconds before fight: prepot, flame orb
Combat: ABx4, PoM AB, pop all cd's and mana gem AB spam till ~30% mana (first burn phase) ~30 secs
Evocate 5 secs
AB Spam to ~55% mana (mini burn phase) 20 seconds
Flame orb, use all available missile procs (you'll get a bunch). This takes about 15-20secs to get back to full mana if done properly
This leaves me with 1min20 seconds on evocate and I only need to do the 'conserve phase' for about 35 seconds before my next burn phase
rinse and repeat.