Social work, and even therapy, to a lesser extent, are very versatile professions. There are such a wide variety of practice settings out there - different populations, treatment modalities, and work environments. Where does one even begin in trying to find the "right" fit?
That said, there are better and worse "fits" out there. Hone in on better fits by prioritizing your needs and work preferences at this point in your life ( knowing that they might change over time - say, if you have a child, or your child leaves home). What are your must-haves, and what are your "it would be nice, but isn't crucial" preferences? Logistical preferences are probably easier to identify (e.g., shifts, days of the week, working from home, total hours, commute, etc.). However, as in my example of people mattering more than shift to me, it's often less tangible things that matter more - feeling like the work is important, for example, or finding some aspect rewarding, or connecting with colleagues, or feeling valued. Some of these intangibles you can plan for (e.g., someone with religious objections to abortion would not find it meaningful or positive to work in a family planning clinic), while others are harder to screen for in a job search (e.g., most agencies don't reveal staff drama during the interview process - you only find out once you're in it what this agency's drama is...knowing, of course, that there is some sort of issue just about everywhere). When things come up as you go along, you have to weigh your priorities and determine if the positives (the reasons you took the job, for example) outweigh whatever the negatives have turned out to be.
To narrow things down further, you'll need some self-knowledge. Insight is not just for clients! We have to recognize our own strengths - and weaknesses - and play to our strengths. We have to know our personalities well enough to know what we can, and can't, do successfully, or satisfyingly. For example, do you enjoy or feel isolated by working alone? Individual therapists tend to spend a significant amount of time alone, with clinicians who work on treatment teams tend to be surrounded by other people most of the time. I know that, for myself, I can spend a portion of my time alone quite happily, but start to feel isolated after awhile. I enjoy the cacophony that can be team work, as long as the team has mostly positive working relationships (I have low tolerance for cruelty, particularly from those in "helping" professions). Therefore, while the treatment modality I enjoy most is individual therapy, I know that I'm happier spending at least part of my time in a milieu setting with other staff.
It's also important to think about what populations suit your style and personality. For example, some people love children, others do not. What groups of people do you feel some resonance with? Those are the people where it will be easiest to develop empathy (not that it's impossible to empathize with other groups, but that it is harder, and you may be more prone to empathic failures when tired or stressed). The work is more enjoyable when you enjoy your clients!
Finally, I want to return to where I started - it's all a lot to think about, but there isn't a definitive right and wrong answer, and it's always possible to change your mind along the way. These days, most people don't stay in one job for their whole career, and many clinicians take advantage of the field's versatility by varying their work over time. Doing so helps prevent burnout, makes room for changing needs at different points in life, and keeps your perspective fresh. Change is almost always an option when the negatives start to outweigh the positives.
What factors do you think are important in finding a field of practice that "fits?" What have you learned about yourself along the way?