The rotation after level 20

As we said earlier, the rotation gets somewhat more complex at level 20. Personally, I find that Holy Fire makes a strong opener, followed by either Mind Flay (for shadow priests), Smite (for glyphed holy priests) or Mind Blast (for the rest of you). Part of a strong offense is a strong defense, so make sure you always keep Inner Fire up and consider casting Power Word: Shield before tricky pulls.

For the more mana-concious priest, you may find that switching to your wand immediately after casting Holy Fire works just as well. This is strategy is especially useful in 5-man instances when you have an overly eager tank who isn't keen on stopping every other pull to let DPS regen their mana.

Regardless of what rotation/priority you choose to employ, be sure to keep plenty of Melon Juice, Sweet Nectar or Moonberry Juice on hand to regen your mana when you need it.

• Pro: With Holy Nova and Glyph of Smite, leveling as holy is somewhat competitive DPS-wise with shadow in the early going, especially given the lack of low-level shadow spells.
• Con: Holy priests fall behind shadow priests in terms of damage as they level, with virtually no DPS talents in the holy talent tree's later tiers.
• Pro: With a shorter wait time than DPS players, holy priests can level quickly through the dungeon finder tool provided they're okay with healing instances.
• Con: Holy priests crap sunshine, puke rainbows and cuddle with gnomes. They also get their advice from Dawn Moore.
• Con: People you don't know will whisper you and ask you to heal instances. Incessantly.
• Con: You will experience the inherent shame of being a holy priest. Gross.

• Pro: The shadow-exclusive talents of Mind Flay (level 20) and Vampiric Embrace (level 30) are far better than any holy talent you can obtain at those levels, at least in terms of soloing.
• Con: Shadow damage can be weak at lower levels. It doesn't noticeably outpace holy damage until level 40-50, and the best shadow talents (Shadowform!) are only available in the later levels.
• Pro: Shadow priests are exceptionally fun to play in the end game, and you'll be well ahead of the learning curve when you ding level 80 if you've been leveling as shadow.
• Con: After level 40, casting holy spells gets a whole lot more difficult because they throw you out of Shadowform.
• Pro: Only shadow priests can apply to join the Fox Van Allen fan club, which allows member's only access to cool Fox Van Allen iron-on transfers, an official membership card, exclusive posters for your locker and the Fox Van Allen newsletter!
  

Once you hit level 30, most of the quests you'll find are in "contested areas," so be prepared to get ganked if you're on a PvP server. Both factions will find quests in Arathi Highlands, Desolace, Alterac Mountains and Stranglethorn Vale. When you get closer to level 40, quests will start becoming available for both factions in Dustwallow Marsh. Horde characters will find quests starting around level 35 in Badlands and Swamp of Sorrows.

Upgrading your equipment

As was the case on your way to level 20, one of the best places to find new and improved equipment is by running instances. There are an awful lot of 5-man dungeons available on your way to level 40. I won't list them all here, but I will highlight a couple of key instances and some of the loot inside that you'll want to keep an eye out for.

• Stormwind Stockades The Stockades are available at a minimum level of 15, but contains mobs tailored for characters in their mid-20s. This instance is noteworthy for its lack of loot -- there's not a single blue drop to be found in the whole instance. Alliance characters can complete a long quest chain to eventually earn a blue ring ... but it's terribly itemized for priests. Stay away unless you're obsessive-compulsive about achievements or have an overpowering desire to farm Wool Cloth.
• Gnomeregan Located in the heart of Alliance territory with plenty of Alliance-only quests, Gnomeregan is definitely an instance intended primarily for Team Wrynn. Still, there's a really good reason for Horde shadow priests to run this long (sometimes painfully long): the Electromagnetic Gigaflux Reactivator, one of the first, best cloth headpieces for casters in the game. Be warned, though, the drop rate is low and competition is likely to be high; even paladins, shammies and druids may want to roll for it, despite it's being cloth. Gnomeregan is advisable for characters at or near level 30 or for any character at any level with an overpowering desire to slaughter gnome rejects.
• Scarlet Monestary Consisting of four separate instances within throwing distance of Undercity, the Scarlet Monestary is something of a rite of passage for most Horde players starting around level 30. (There are a few select quests for Alliance characters, too.) There aren't an awful lot of great drops out of SM, especially for players decked out in heirloom gear. One notable exception: Whitemane's Chapeau, another great cloth headpiece that drops from the cathedral wing.
• Uldaman Players from both factions will find quests to complete in Uldaman as they near level 40, but the instance is clearly geared towards Alliance dwarves -- at least from the lore perspective. Besides some pop culture Indiana Jones references, you'll be able to find great cloth drops: the Stoneweaver Leggings and Revelosh's Gloves. Since the latter comes with a random enchantment, you'll have to keep your fingers crossed for some good RNG luck.

Oh, and let's not forget -- you can also get some great equipment by spending honor at your faction's PvP vendors. When you first hit level 28, you can buy some great PvP gear (that doubles as great PvE gear) from the Arathi Basin quartermaster. Especially notable: the Highlander's Cloth Boots (Alliance) / Defiler's Cloth Boots (Horde), which provide valuable stamina, spellpower and a terrific 8% boost to your run speed. Cloth waist pieces are available for purchase in Arathi at level 28 as well. The cost: a mere 300 honor for either.

Don't forget to make a stop at your Warsong Gulch Battlemaster as well. Once you hit level 28, they'll have upgraded versions of their cloaks and rings available for sale.

If you liked this article, you may also like the other parts of the "Spiritual Guidance leveling guide" series:

• Priest Leveling Guide, Levels 1 through 10
• Priest Leveling Guide, Levels 11 through 19