I have been leveling my alts with this method and wanted to share. This is for low levels and till 78-80. Basically buy all heirlooms and stack all exp giving items and potions if possible. Find a high level friend (level 100), Go to 'Ruby Sanctum' heroic 25 man, you get %50-60 experience per run. Simple, fast, efficient. I haven't tried other raid or after level 80 raids, but going to try, if i can find any other guide for leveling low level alts i would be happy to share. Thanks for reading! Have FUN!