I think some discussion is needed about how to (and how not to) do a gear plan. For starters, do not plan to go straight from the gear you currently have to the 'best in slot' in every slot. Your character has 17 gear slots. It will lead to a lot of frustration (not to mention reduced raid performance) if you held out for only a single item in each slot. Similarly, don't scoop up every upgrade along the way if others can use it too. If you're on a DKP system or a golf scoring system, it will send you negative really fast. If you're on a open /roll system, it will reflect poorly on you to upgrade a slot, then upgrade the same slot a short time later. The idea is to gear up the raid in an efficient manner so you can get encounters on farm status quickly. With those two extremes out of the way, 1) Using http://www.wowhead.com/ or other item site, go through each gear slot and draw up a list of candidate upgrades. I usually filter by iLvl around the content we're doing. For example, if you're targetting Naxx 25 (iLvl 215), set your filter one tier below at iLvl 200 (Naxx 10) and one tier above at iLvl 226 (Malygos, KT, Sapph). By setting your filter wide, you can now gauge on a per slot basis:
1a) Are there gear upgrades available through crafting that are near the iLvl I'm looking for.
1b) Are there gear upgrades available through 5 mans or 10 mans that are near the iLvl I'm looking for.
1c) Are there gear upgrades available through tokens that are near the iLvl I'm looking for.
1d) Are there gear upgrades available through faction reputation that are near the iLvl I'm looking for.
For gear slots with an alternate upgrade path, you have more freedom to pass on loot in that slot since you can obtain the upgrade elsewhere. If there's a best in slot item that you really want in that gear slot, you can fill it via the alternate path to tide you over until the best in slot item drops. 2) As the raid progresses through earlier encounters, gear up at a rate that matches others in the raid.
2a) If you really want a best in slot item in a particular gear slot, upgrade this one last as long as others can use the loot. If the item is going to go to an offspec or be DEd, you should take the upgrade.
2b) For items that are expected to have a lot of competition, be prepared to upgrade this with an item that is not best in slot. It's bad enough that an item has a % chance to drop, it's even worse when a lot of people are interested in it. Since most of these are concentrated on the later encounters, you need to have reasonable expectations (e.g., KT has a best in slot ring, cape, and weapon -- I should not plan on getting all three; I should upgrade the three slots following 2a above). Remember, by inefficiently gearing yourself and the raid up, it will take longer to get content on farm so that items will drop often enough for people to get closer to the gear they ultimately want. -HP