You will need to make the effort to meet faculty members and get involved in seminars and independent study until you find your place. Try to get office space, at least once you have a research advisor. Without a desk, it can difficult to make contact with fellow students or your advisor, and a place to work away from home is quite important. If you think you might want to become a professor, you might want to volunteer to TA for a semester in order to get some experience. This can be helpful in deciding whether the academic life is right for you, and it is a definite asset during a search for an academic job.
Some graduate programs require teaching as part of the Ph.D. requirements.
If you have a full or part-time job outside the university, you may feel that you are between two worlds, without belonging to either one. Neither the university nor the workplace is well adapted to dealing with the other, and each may place demands that are incompatible with those of the other. Your biggest problems may be the double commute, scheduling difficulties, and isolation. While you are taking courses, each semester will bring challenges of how to arrange to be on campus at the necessary times without unduly hampering your work. Electronic mail and remote computer access will alleviate some of these problems but not all of them.