Building a healthy colony is an art. There are so many ways to mess up. Typical mistakes are
Employing wrong people - one troublemaker can spoil the work of others.
Not accounting for physiological specifics of humans - humans need certain electromagnetic vibrations, foods, air, exercise and such.
Not accounting for specific psychological stimulations humans are used to: the humans would be under cultural shock and deprived of many habitual psychological stimulations. Some of these are easy to reproduce, for example, watching movies may help treating many deprivation syndromes.
Giving humans too much freedom to fight to each other. Some humans are used to rigid hierarchical structure, but most Westerners are used to very flexible democratized structures, where people behave as equals and everyone is allowed to question everything. Humans typically tend to develop their own hierarchy. I suggest giving humans some of self-governing, consult with them how much freedom they want and how do they want to self-organize. Adding aliens to the team may also be a good idea.
Giving humans too little freedom, too much guidance and blocking their creative energies. This is rather obvious. Energies have to flow in healthy ways.
I will say more on item 1: employing wrong people.
Obviously, different people will be right for different jobs. People vary much in their adaptability. In general people adapt really well to different environments, but too quick adaptation is often traumatic. I recommend softening the cultural shock as much as possible. This way you will have more genuine humans who keep their mental integrity, traditions, habits, perceptions and so on. One of the purposes of the colony is to experiment with exposure of humans to aliens and optimize the process of cultural transformation. So every new human arriving to a colony is a test subject which will show you how we can adapt.
One of the things you can do to soften the transformation is to prepare each new human for the experience by giving them a bit of guidance how to take it. Understand that humans have similar cultural transformation experiences all the time. As a human grows, she is exposed to new environments many times. Going first time to primary school, going first time to college, going first time to work, retiring, staying for the first time in a hospital, staying for a first time in a hotel, taking a cruise, traveling abroad, and finally emigration. Emigration or going to foreign country to work is a perfect model of cultural transformation. Most radical could be for a Westerner to move to Japan.
I have moved many times and have an emigration experience, which was a very radical change from Soviet to American. It is very much like going to live with aliens. I had some support, although limited, but I was certainly supported by friendly people who knew well how to welcome foreigners. Some of their welcome steps were extremely clumsy. For example, my family came from a country, where we were extremely poor. First thing my hosts did was to order us a limousine - an extremely luxurious car to move us from an airport to our hotel and they also gave us a luxurious hotel. This was to us a waste of money. We would rather have this money in cash and send our relatives and friends who were in desperate poverty. That was how we took the luxury. We were used to ascetic living and didn't enjoy the luxury, we rejected it as an extreme excess. We are still living quite ascetically in many ways and find luxury immoral.
A very important factor are the terms of the contract. Ideally the human has to perceive the joining the colony as a voluntary action done after a careful consideration and being informed about the conditions in best possible way. Obviously, you are limited in ability to tell the volunteer human everything about the colony's mission and conditions, but at least there should be an honest attempt done to give as much information as possible and to clarify the terms and the mission as well as possible upfront. A human would need some time for consideration. Hours are a stretch, days are better, weeks are maybe a bit too much in your circumstances.
Among most important factors are the terms of termination of the contract. Does the human have the right to return to Earth? In which circumstances? Would this return be terminal, or there is a chance to visit and come back?
What would be the terms of leaving the colony and being hired or going to live or travel elsewhere off-planet?
How secret is the mission? How secret is the intention of the human to go serve in the colony?
Take a note also, that usually humans are hired by their direct supervisor and at the time of hiring are given clear instructions what are going to be their relationships and how the reassignment of the relationships would normally take place. There may be many unexpected misunderstandings here, and you could prevent them up-front.
Humans are very flexible in giving part of their freedom but also very sensitive to the condition of "never". To contract for "never" returning to Earth would be very tough on many humans. By pressing on this term you would positively select for psychopaths and negatively select against good humans.
Communication with the Earth would be another important factor. I would recommend to negotiate with every human the conditions of their service in the colony.