Which type of treatment?
It's an odd position to be in. You want help but don't know what kind, so you don't know where to turn. There's no simple guide or flowchart. Here's one way to get you started.
First, the emergencies. Are you failing to attend to your basic needs (food, clothing, shelter), or are you at imminent risk of seriously hurting yourself or someone else? If so, go to an emergency room for possible hospitalization where your basic needs can be met and physical safety assured. Likewise, to see a mental health professional in an office, you need to be able to make and keep an appointment, get yourself there, and sit down in a chair and talk for a while. If these aren't possible, you probably need a "higher level of care." This usually means a hospital, partial hospitalization program, or day treatment. The basic idea is to utilize more intensive services if, and only if, less intensive options won't do.
If substance abuse (including alcoholism) is the main problem, then contact a professional who specializes in this, or go to an ER if your situation is severe, or if not, consider 12-step meetings such as Alcoholics Anonymous.
Aside from these extreme situations, we're left with the many, many people who function well enough, but who seek help for troubling thoughts or feelings, unsatisfying or conflict-ridden relationships (including marriage), a stalled career, lack of direction or meaning in life, and so forth. There are many types of "helpers" out there. How to choose?
One basic distinction is between non-professional and professional helpers. The former include friends, kind relatives, suicide hotline volunteers, peer-support groups, the 12-step meetings mentioned above, well-intentioned but untrained people on the internet who run websites and blogs about particular disorders, the community of usually anonymous commenters they attract, and so forth. The advantages of turning to non-professionals is low or no cost, sometimes more empathy (they've "been there"), anonymity, and avoiding any shame one might feel about seeing a professional.
Mental health professionals (MHPs) include a number of disciplines: nurse practitioners and psychiatric social workers, marriage and family therapists, trained counselors including pastoral counselors and "life coaches," clinical psychologists, psychiatrists — and trainees in all these fields. (This list is not exhaustive.) Non-psychiatric physicians, e.g., family doctors, offer brief counseling and common psychiatric medications as part of a medical appointment, but are not MHPs specifically.
Why see a MHP? Because we can often help more deeply, and in different ways, than non-professionals can. In addition, MHPs take responsibility for our work, abide by ethical codes, and have standards of practice. This doesn't guarantee that any given professional will be helpful, or even ethical — but it's an important start. MHPs know mental health in much the way professionals in other domains know their fields: not infallibly, but with depth and comprehensiveness that comes from years of study and experience.
Let's say you're interested in seeing a MHP. Of the types listed above, counselors are trained to offer support and advice, i.e., to counsel, not to change the person being counseled. If you'd like to discuss the pros and cons of different career paths, for example, a job counselor could be the perfect choice. Psychotherapy is different: it aims to help a person change how they think, feel, or function. Although psychotherapy takes the form of a conversation, it is a therapy, a treatment. I discuss different types of psychotherapies, and therapists, on the next page.
One more distinction to make is between medication treatment and psychotherapy. It's important to realize that psychiatric medications aim to relieve symptoms. None cure a "chemical imbalance" or get to the root of the problem. They can't, because we don't know the biological roots of any psychiatric disorder. It's a curious historical fact that once we discover the biological cause of a psychiatric disorder, it isn't considered psychiatric anymore.
There is a crucial role for symptomatic treatment in psychiatry. Severe anxiety and depression are miserable, OCD can be paralyzing, mania can ruin lives. A mental health orthodoxy that withholds such treatment on the grounds that it doesn't address the basic problem is heartless — tantamount to an oncologist refusing to prescribe pain medication because it doesn't fight cancer.
I wrote that we don't know the biological roots of any psychiatric disorder. However, the same cannot be said as plainly about psychological roots. Although theories differ and are hotly debated, psychotherapy has been shown to relieve many types of troubling thoughts, feelings, and behaviors in an enduring way, long after treatment ends. Offering only symptomatic treatment, e.g., medication, when enduring change is possible is tantamount to our oncologist prescribing only pain medication. This is heartless in a different way, and reflects a therapeutic nihilism that has no place in oncology — or psychiatry.
Medication and psychotherapy are not mutually exclusive. It's common to receive both. Today this usually means a physician, psychiatric or otherwise, who prescribes meds, while a non-physician provides therapy. "Split treatment" sometimes offers a cost saving, and in many locations this arrangement is more readily available than receiving both services from a single doctor, i.e., a psychiatrist.
There are real advantages to not splitting treatment as well. A psychiatrist who provides both medication and psychotherapy will often rely less on the former. That is, dosages may be lower, with less tendency to add additional medications ("polypharmacy") for each new symptom or to counter medication side-effects. Also, symptoms are more apt to be seen in context, not in isolation. The doctor and patient can identify symptom patterns related to psychological dynamics, as when an antidepressant suddenly "doesn't work" or side-effects suddenly arise in the context of stressful life events. More generally, the psychological overtones of interacting with the prescribing doctor — reporting symptoms, receiving a prescription, then reporting back on its effect — are as central a part of a dynamic psychotherapy as musing about one's childhood or marital relationship.
In summary, if the situation is not an emergency and can be addressed in a non-acute setting, the choices are to seek non-professional help or the professional kind. When consulting a MHP, consider whether you wish to change something in yourself (thoughts, feelings, behavior). If not, consider a counselor or coach. If so, consider psychotherapy. Medications can be a useful addition for symptom management, particularly if viewed in the larger context of the overall problem.