How to build relationships with colleagues as new faculty member? I have just started a new job
as an assistant professor in a tenure-track position.


What are the most important things that I can do
to build good working and social relationships with my colleagues?
Related to the above question, 
what are the tasks that require faculty members to work together,
and how do I work well as a member of a team in such settings?


Background
I felt that I did not do a good job
in developing relationships with other students during my PhD years.
I observed that other students seemed to go for lunch/coffee,
hang out together, go out to a bar or for a movie,
but somehow I did not participate in such social activities.
I hope that I do not make the same mistakes
as I start my new job as a new faculty member.

Clarification
in response to the question
How do we have to imagine that you did not participate in such social activities?

I did take part in some department social events,
e.g. a student retreat, student BBQs,
the intermural soccer team, open houses for prospective PhD students, etc.
I didn't join people for coffee
because it is not a habit for me to drink coffee.
Perhaps I should have joined not for the coffee but for the company.
As the stress oh PhD piled up I became more insular
because it takes energy for me to socialize with others
and I wanted to conserve energy.
Now that I look back,
I feel that if I had spent a little more time with other people,
I could find a happy medium where I am neither
too exhausted being with other people (too much social interaction)
nor feeling lonely (too little social interaction).
Solve the social things by being proactive. Go to your colleagues individually, after committee meetings, or during their office hours, introduce yourself as the new guy, and offer to buy them lunch or a coffee. If colleagues go to lunch after departmental meetings, politely see if you can tag along. The "somehow" in your question is indicative of someone who did not look for such opportunities or dodged invitations. Lunch is probably the easiest time for colleagues in a work setting to begin their socialization. Everyone eats and almost everyone like some company. 

As best as I can tell, there are only a handful of things that bring faculty members together for forced work, e.g. departmental committee meetings. That being said, departments have social and semi-social functions. Attend as many as you can. Volunteer to help with student move-in at the dorms. Volunteer to be a marshal and graduation ceremonies with other faculty. Find a hobby and check out the university club (exercise oriented ones like cycling, rowing, and running tend to be popular). 

Solve this problem like it was your PhD. Set goals and be deliberate. Also, be friendly.