While my humble outline here may not be enshrined amongst the great writings on leadership that are available for the betterment of leaders everywhere, it certainly represents the sum of experience and belief demonstrated by many boss-types I have worked for and with. I therefore submit this for consideration toward your professional success as a controlling boss and the success of the group (we'll call them a team) over which you have control.
1. Encourage Training. This is important. This is really important. You want your testers (they like being called testers better than being called them peons of serfs) to believe that you want them to get better at what they do. Make sure they know that training is important to their career development. You want to make sure that the training they get is company sponsored training. Other stuff like, well, that encourages them to think is to be avoided, discouraged and downplayed.
2. Discourage Outside, Corrupting Influences. We want the people working for us to only consider the information we present to them as being relevant. When people express an interest in something they read about, maybe on the web somewhere, let them know that it is important they "get all the facts" before deciding to learn about it. Have them go looking for examples of companies where these wild, new-fangled ideas have actually worked. When they come back with some examples, make sure they know that these are not really solid examples because they are from outside the industry you are in, or are multi-national, not multi-continental (other way around works as well!) or they are in environments that are regulated differently than the environment we are in or... any number of reasons why "that won't work here."
3. Encourage Engagement. This is important, too. You want them to feel warm-fuzzy thoughts in their tummies when they think of the company. They want them to think, "Wow. The bosses at TLA* really DO have my best interest at heart when they tell me to do something and I'll be rewarded later. I hope I get a pony as my reward." This is particularly effective in large urban areas where the belief that a pony might be the "reward"is a complete impossibility where the large urban area does not permit ponies within the city. The idea is similar to "A rising tide lifts all boats." That is true, as long as the boats in question have plenty of slack where they are tied-up or moored. We want to be certain there is no slack at all for the
*TLA: Three Letter Acronym (thanks to Matt Heusser from whom I blatantly stole that concept.)
4. Discourage Uncomfortable Questions. Well, not really discourage them, just redirect them to be discussed "off-line" so people are not side-tracked by "side issues like this." The beauty is that when people ask questions you don't want asked, you can appear to be concerned with addressing their concerns completely, and at the same time keep those questions, and the discussion around them, from causing discomfort to the rest of the laborers. This allows the quick-thinking manager to isolate the trouble, and trouble-maker, pat their hand and say "there, there" and reassure them that everything will be fine. The upside for the manager is the next round of "synergy actions"/"staff rationalization"/ happy-sizing / down-sizing, you already have at least one candidate for "change agent" status.
5. Encourage "Extra Effort". Getting people to get things done when most people looking at on schedules that simply can not be achieved at a mere 45 or 50 hours per week per person can be a particular management challenge. One effective technique is to make the "casual" observation that contracts are tied to these dates and the delivery must be made on time. Of course, if the delivery cannot be made on time, well, "other options" will need to be considered. Then, this leaves open the carrot of the "stretch goal" set a week or two ahead of the "mandated goal" - where completing the project early may get recognized with a raise (or at least not a pay cut) IF all the other projects get done on time or early as well. (Notice the subtle conditional statement slipped in there, its a possibility, not a certainty.)
6. Discourage Process Questions. Yeah, this is kind of a big deal, too. The Process is sacrosanct. You are not in a position to suggest improvements to the process until you have moved through it completely, successfully at least once. Well, maybe twice or three times (because success is a habit, after all.) If people are having problems working through the process, it is because they are not doing it right. If they do it right, they have no problems.
7. Encourage Participation. This one is important, too. One way to handle trouble-makers is to get them involved. If someone asks questions, like a lot of questions, ask if they'd be willing to participate in a study group that has been created to look into that very issue they ask questions about. It is a great way to get all the people you need to keep an eye on in one place. Additionally, because this must be done in addition to the project work (see number 5 above) it will be one more way to drain them of extra energy to make trouble. If they still complain, ask if they have been "participating" with the study group on the issues they are complaining about. If not, you just transferred blame to them! That is good leadership.
8. Discourage Independent Thought. This is a hard one and it may take all the previous lessons to pull this one off. You want people who can do decent testing. That means you may have to hire people from outside the company. That also means you may need to hire people with some level of experience. This experience may have given them ideas of their own, or at least carried the lessons they learned from previous jobs with them. Encourage them to "observe and learn" how things are done at your company. Then, use the ideas from number 6 above to get them to become fully assimilated into the mindset of the company. This will, hopefully, keep them from thinking something is wrong with the company by reinforcing the image that the problem is with them (after all, they left their old job because of why?)
Lessons Learned - I've seen these ideas applied often at various shops. Where two or three are used effectively, the result has been promotion for the manager who did such fine work. Of course, the fodder complained and whined until they were replaced or learned that complaining led to them "seeking new opportunities" - which pretty sell stopped the complaining. In public. Which is as good as stopping complaining altogether.
Remember: Managers are the keepers of the Truth. The Guardians of the Holy Flame of Knowledge. Facts can change and shift and using these techniques what the Manager agreed to on Monday, on Tuesday, if you are effective, you can disagree with and explain that the staff misunderstood. This technique is good for keeping them from ever really understanding what is expected, which is even better because the money set aside for raises and bonuses will go into your pocket.