I'm an 80 Mage, I've done 55 Emblems of Heroism worth of Heroics(262SKS, 36 Badges of Justice from regs) running instances every day and night that I can.
I just did my first Sarth 1D 25man, which was awesome.
I've been kinda unlucky on drops(I have only Epic bracers, from H VH) no epics from HoL or the like.
I have both Frost and Arcane specs. As Frost for boss I pop Elem, Mirror Image then hit Icy Veins, my trinket, and spam Frostbolt until Veins wears, hit Cold Snap, re Icy Veins and pop Elem again when he vanishes.
My DPS blows.
As Arcane I prep Presence of Mind then toss out Mirror Image, Slow, then hit trinket and Icy Veins followed with Arcane Blast, hit Arcane Power and spam Arcane Blast 2 more times, then Barrage(or Missiles if buff is up). I then sit back on Blast x3 -> Barrage or Missiles(if buff) and reapply Slow as it fades.
My Armory is here and I'm working on it but I should be doing 2.5k+ and I don't do 2k on anything but trash...