Counseling may be for you if you are continually finding yourself repeating the same behavior over and over with the same disappointing or unhealthy results. Another sign is when your friends tell you directly that they "don't want to hear it anymore!" in response to your constant complaining about the "same old stuff."
Commonly, people find that when they are in crisis it helps to have a neutral party help them sort out the situation. In the case of chronic or long term unhappiness, if you realize that you are "somehow part of the problem" but you can't seem to figure out that somehow, then counseling is one avenue to travel.
In general, counseling or psychotherapy can be a place to turn when you need to find practical solutions to practical problems. The difficulties some people bring to counseling or psychotherapy are not about finding practical solutions, but are about understanding the internal motives or motivations behind their behavior.
Whether or not you will benefit from counseling or psychotherapy is dependent on several variables, as follows:

First, whether or not you entered counseling under duress. If you did, it is unlikely that you will change your opinion about whether you belong in counseling, and whether it can, indeed, be helpful to you. However, in some instances, those who arrive at their first therapy session under duress do, in fact, leave feeling relieved. Finally, they were able to tell someone what was really on their mind, and they decide to continue with the attitude that they are going to make the best of it.
Second, how you feel about the therapist or counselor sitting before you will also affect whether or not you will benefit from the experience. Some therapists are more than qualified to help, but if the chemistry between the two of you is not there, you may be wasting your time. Granted, it's sometimes difficult to determine the difference between a lack of chemistry and one's own feelings of defensiveness. After all, undertaking the rigors of self-exploration is not necessarily an easy task. For example, the counseling process may at times lead you to feel some painful feelings that you previously didn't even know existed.
Needless to say, the problem(s) you bring to therapy or counseling should be discussed between you and the therapist. With the counselor or therapist, determine whether or not, in his or her opinion, the difficulty is one that honestly requires therapy. If the two of you agree that it does, then the therapist must somehow be able to convey to you that he or she is qualified to assist you in the matter.
Third, accept no guarantees that therapy or counseling will be a success. Sure, it would be nice if such a guarantee could be made but the fact is that no one can predict the future. So beware of the therapist who tells you that they know for a fact that you will benefit from therapy. There is a big difference between being told you "can" benefit versus being told you "will" benefit.