The Raider Tank
Once a tank has proven themselves beyond a doubt that they are capable of handling the tanking needs of the guild, they are ready to become a raider. A raider to me generally requires less direction and input than applicants in order to do their job correctly and efficiently.
However it does not mean that a raider still doesn't need leadership and a gentle helping hand. As was previously outlined, the best way for this helping hand to assert itself is through the class lead. The raider level tank will already know that the class lead is the person to go to for information about the raid and strategies, so it's a natural progression for the class lead to assume the long term responsibilities of helping the tank progress in their tanking career.
One big difference from a class lead helping an applicant tank and a raider tank is that for the applicant tank, the class lead will probably want to assume more of a "Go over here and kite Illidan's flames along this path." While with a raider tank the class lead should take more of a conversational approach to strategies and direction, "From my understanding of the fight, the best way to kite Illidan's flame is along this path, what do you think?" When the class lead approach a raider level tank in this fashion it not only shows that you value their input (which you should), but that they have a chance to present dissenting opinions.
Some may question why this approach can't be used with applicant tanks. There really isn't any reason it can't be. If the applicant tank has sufficiently impressed upon you and others their ability to handle themselves according to the guild's needs, then it's definitely worth having a conversation or two (dozen) about strategies. However if my experience in WoW leadership positions has taught me anything, it has taught me that not everyone know how to setup and integrally plan an encounter. Running into a tank that, while they might have a good understanding of the class mechanics and what not, cannot see beyond their own class and job, can take valuable time away from the whole raid while you learn about their views (or lack there of). While these conversations can generally be had outside of raid time, it is important that they do not happen very often (or at all) during everyone else's time.
The senior tank is the tank has been in the guild for a few months, and things are good. They have shown up with near perfect attendance and are a cornerstone member of the guild. We all know these people, and for some reason, they are almost always the tanks. I'm sure it has something to do with the psychological profile that attracts people to tanking, but that is for another article entirely.
A senior tank needs to be respected and made to know that they are still a valuable member of the guild and raiding corps, even when bringing a new tank on board. A senior tank will have spent a lot of time and energy on the guild, and is committed to the long-term survival and success of the organization. Sometimes a senior tank is an officer or class lead, and in these cases it's up to the guild's leader to make sure they feel represented and respected in all aspects of the guild's functioning.
More or less the senior tanks are going to be the ones to define how your tanking corps behaves itself and feels to others. If the senior tank is a mean and vengeful person, expect the rest of the tanking corpse to act that way too. After all, if the senior tank has been around forever and is a successful tank – why not emulate their behavior?
However on the flip side, if the senior tank is a level headed individual who knows how to have a good time and be serious when he or she needs to be, then the tanking corps will reflect these values as well. It is important that the senior tank realizes this if they're not in an official position of leadership. If their behavior or attitude ever deviates from what the guild leadership feels is appropriate, a gentle reminder can work wonders. "While we all understand where you're coming from, some of the new folks don't and they might get the wrong idea." This kind of positive and encouraging words of leadership can quickly make everything good again.
The best way to keep a senior tank around is to let them do what they want. This might seem contradictory to things that I've said before, but if you think about it for a minute – it's really not. The senior tank will have the best interest of the guild at heart and in mind, so they are very unlikely to do things which will be detrimental to the organization (however of course, some person or some group should always be on the lookout for bad decisions – and that's what officers are for). If the senior tank wants to take a night or two off, let them. They've more than earned it. If they want to take a few weeks off to collect themselves or to focus on a job, that's a-okay too. They've helped built the guild and raiding up to where it is, and they deserve to take a vacation just as if they were vacationing from a job (that too is a topic for another time).
The Mentor Tank
I've left for last perhaps the most ambiguous stage in a tank's life: the mentor stage. A tank that acts as a mentor perhaps does nothing more than provide an ear for those that want to talk, or provide detailed advice on a given subject. They are there for everyone – not only themselves or the tanking corps. They want to help everyone understand why threat sometimes takes a back seat to survivability, and they want to be sure that everyone knows everything they need to in order to have a successful tanking experiencing.
In my opinion these are qualities that are necessary in order to be a class lead or have a leadership position of any other sorts within a guild.
The mentor tank type person is going to stick with the guild through the thick and thin of it. The only real threat to them leaving is if the applicant type tanks refuse to work with them or others to accomplish the guild's goals. Often times they will put up with a lot, but eventually they may burn out and suddenly depart one day. And it's these departures that usually hurt the most – because it's then that you realize how important they were to the guild.
The best way to avoid these types of departures is to be sure that the recruitment tank is talked with honestly and openly. Be sure that they know exactly what to expect, and what is expected of them.
Putting it all together
When you look at all these different life stages of a tank in the guild, you can quickly begin to realize how vital it is to look at each person as an individual and help them with their individual situations. What I've laid out here is not rigid standards to classify each tank in; some tanks may be part senior tank and part mentor tank, while others may always exist between a raider tank and an applicant tank. But in general if you find a dedicated and motivated individual, they'll follow these steps as they become a great member of your tanking corps.
The important thing to remember that in all phases of a tank's time with the guild it is important to be respectful and honest. The tanks job is hard, and with a bit of basic values applied and understanding of their specific situations, they can be a long lasting and heavily contributing member to any guild.