How to gear up for raiding is an issue of concern at present, most of the players online want to find the shortcut for them to gear up without difficulties. So we think it the time for us to take this opportunity to make mention of this topic in detail, see the following information.
   First thing first, decide what spec you want to be. This is a bigger change for some classes than others. Decide whether you want to tank, heal or DPS. For example, most of a raiding hunter's points can be in the Beast Mastery tree, but some talents like path finding are useless for raid DPS.
Install Atlasloot on your computer will make finding gear much easier, since it's all listed in one place, under an easy-to-navigate interface. This is particularly useful when you can't find a gear list for your class, or it's unclear where a certain piece of gear comes from.
Most of the high-level crafted items are Bind on Pickup, so if you want to have it, you'll have to be able to make it. Engineering is an excellent profession for Hunters, Rogues and feral DPS Druids, while tailoring is great for Mages and Priests. It will take a bit of time to collect the mats to create most of these pieces of gear--as well as gold to max out the profession--but it's an easy way to get some top-level gear for your character if you'll put the time into it.
Find out what reputation rewards are upgrades for you, and what will bring up your stats to your guild's minimum requirements. The Shattered Sun Offensive, Lower City and the Sha'tar are all factions that give good rewards for a variety of classes. Once you know what gear you want, start grinding reputation through quests, instance runs, dailies and donations.
To run the high-level five-man instances, you should get groups together such as Steamvaults, Shattered Halls, The Caverns of Time and the Tempest Keep are just a few of the many Outlands instances you could farm for gear. Continue to run them until you get all of the useful blue or high-quality green gear upgrades out of them.
After you've geared up a bit and your group can handle it, move up to heroics. These are harder versions of Outlands instances tuned for five well-geared level 70s. Many of the bosses drop epics, and some of these are better than what you can get while running the early raids. For example, there is an awesome healing trinket that drops off Kael'thas in heroic Magister's Terrace, as well as a great hunter chest piece. Again, simply browse Atlasloot or Wowwiki to find out where you should be looking.
To consider PvP gear is a must. If your character is DPS-based, take a look at the arena season gear, or purchasable reputation faction PvP gear. This will take some honor grinding, but you can get some good upgrades with PvP gear. Resilience is mostly useless in raiding, but the other stats are usually for high damage as well, so it can benefit your DPS character. There are some good healing upgrades as well, but it's often easier to get healing and tanking gear in PvE content rather than PvP. Just compare the stats and figure out what's best for your character.
Remember that a lot of guilds have favored specs for raiding. It is that Protection Warriors, fire Mages, restoration Shaman, beastmaster Hunters and holy Priests are all specs that most people want, and they'll probably expect your character to be. So frost mages, retribution paladins or DPS warriors might have a hard time finding a spot if they're not willing to re-spec.
You can pug Karazhan but if your own guild isn't fielding runs, you might want to find another guild or a guild that has empty raiding slots that you can fill. Raiding requires other people, so make sure you have some way of finding other people to run with.
In order to get your gear ready for Karazhan, these are only suggestions for you. The rest of the gear you'll need to progress to Gruul's Lair will drop in Karazhan. Know your stats well and what you should be focusing on will help you find the best gear for your class and spec.