Here's a guide for Vote Points and Healer Priest (Holy or Discipline spec) PVE for WoW version 3.3.5a. Please feel free to share any suggestions if you are experienced with Healer Priests.
I often run out of mana. Do I need more Intellect or Spirit? Do not gear for intellect if you are often running out of mana. Gear for spirit instead. Spirit generates mana during combat and you basically want your in-combat mana regeneration to be as high as your in-combat mana expenditure. You can do this by increasing spirit and also by reducing the mana cost of your spells using certain trinkets. Also be aware that intellect can regenerate mana faster than spirit if mana percentage restoration buffs are in effect (e.g. Replenishment, Shaman mana tide totem, Priest shadowfiend, etc).
Haste vs Spirit for newbies: If you keep running out of mana, get more Spirit. If you have too much unused mana during combat despite healing the party nonstop, then get more haste. Haste will allow you to cast heals faster which will also use up your mana faster.
Spirit vs MP5 for newbies: Spirit and MP5 are similar and both of these stats will regenerate mana during combat, even while casting spells. Most items with MP5 are either plate or mail armor, thus NOT usable by a priest. However certain items like cloaks, trinkets, necklaces, and rings contains MP5 which WILL work fine on priests. In WoW Cataclysm, Mp5 no longer exists and all items with Mp5 got converted into Spirit. Also read the next post in this thread by Amples for more info.
VP = vote points
S = spirit stat
S/VP = (spirit)/(vote point) ratio. Higher number means more spirit per vote point. This does NOT mean that an item with higher S/VP ratio is superior since you have to take other important stats into account, such as haste, spell power, critical strike, intellect, number and color of gem sockets. S/VP ratio is simply provided to help you decide which items will give the most spirit per vote point, and to help you address any out-of-mana problems.
Crown of Luminescence (VP=89, S=70, S/VP=0.79)
Consider the Helm of Clouded Sight (item level 245) http://wotlk.openwow.com/?item=47694 or Hood of Clouded Sight http://wotlk.openwow.com/?item=47695 which you can buy from Dalaran Cloth Quartermaster for 75 Emblems of Triumph (easy grind via Pit of Saron farming).
Mantle of Dissemination (highest Critical Strike rating) (VP=61, S=52, S/VP=0.85)
Amice of Inconceivable Horror (highest Haste, but lowest Spirit) (VP=61, S=42, S/VP=0.69)
Mantle of the Unknowing (highest Spirit, especially if you gem for it) (VP=61, S=62, S/VP=1.02)
Mantle of Wavering Calm (balanced between Spirit and Haste) (VP=61, S=62, S/VP=1.02)
Soot-Covered Mantle (contains Hit which is useless to a healer but useful for your off-spec DPS) (VP=61, S=49, S/VP=0.80)
Consider the Stiffened Corpse Shoulderpads (item level 264) http://wotlk.openwow.com/?item=50449 which drops frequently during ICC rep farms and also sold at Auction House for around 20,000 to 25,000 gold.
Grasps of Reason (VP=47, S=48, S/VP=1.02)
Consider getting the Royal Moonshroud Bracers (item level 245) http://wotlk.openwow.com/?item=47588 which is frequently sold in the auction house for between 40,000 to 50,000 gold.
Handwraps of the Vigilant (VP=65, S=51, S/VP=0.78)
Mord'rethar Robes (VP=107, S=86, S/VP=0.80)
Consider getting the Royal Moonshroud Robe (item level 245) http://wotlk.openwow.com/?item=47605 which is frequently sold in the auction house for between 60,000 to 80,000 gold.
Starwatcher's Binding (VP=88, S=64, S/VP=0.72)
Leggings of the Demonic Messenger (for Alliance only) (VP=107, S=86, S/VP=0.80)
Legwraps of the Demonic Messenger (for Horde only) (VP=107, S=86, S/VP=0.80)
Consider getting the Lightweave Leggings (item level 264) http://wotlk.openwow.com/?item=49892 which is frequently sold in the auction house for between 190,000 to 210,000 gold.
Boots of Fiery Resolution (VP=65, S=64, S/VP=0.98)
Consider the Sandals of Consecration (item level 264) http://wotlk.openwow.com/?item=49893 which is frequently sold at Auction House for around 120,000 to 140,000 gold.
Sunglimmer Cloak (VP=47, S=48, S/VP=1.02)
Sapphire Amulet of Renewal (VP=47, S=47, S/VP=1.00)
Don't get from vote shop (easy grind for the Ashen Verdict ring and Kirin Tor ring). You can also buy rings from the Dalaran Quartermasters using Emblems of Triumph obtained by farming the Pit of Saron.
Staff of Endless Winter (VP=109, S=84, S/VP=0.77)
The Lifebinder (more Haste but less Spirit) (VP=107, S=80, S/VP=0.75)
Icecore Staff (will have the most Haste if you socket two Quick King's Amber gems into it) (VP=107, S=84, S/VP=0.79)
Scepter of Creation (has the most spirit) (VP=30, S=25, S/VP=0.83)
Petrified Ivy Sprig (less spirit, but can add Haste if you socket a Quick King's Amber gem into it) (VP=77, S=22, S/VP=0.29)
Quartz Crystal Wand (contains Hit which is useless for healer, but useful for your off-spec DPS) (VP=77, S=24, S/VP=0.31)
Consider the Brimstone Igniter http://wotlk.openwow.com/?item=47658 which you can buy from Dalaran Emblem of Triumph Quartermaster for 25 Emblems of Triumph (easy grind via Pit of Saron farming).
Show of Faith (VP=59, S=0, S/VP=N/A)
Spark of Hope (VP=53, S=100, S/VP=1.89)
Titan-forged Rune of Alacrity (for more haste, and doubles as a PVP trinket) (VP=75, S=0, S/VP=N/A)
Abyssal Rune (for more haste, and doubles as a DPS trinket) (VP=72, S=0, S/VP=N/A)
[Please reply with corrections, suggestions, or just to say thanks!]