Minerva -
I asked a similar question recently and got some good answers. In short, the therapist should be qualified and have the right experience/focus for your situation. Also, how do they establish rapor? The last person I went to acted cool toward me, very matter-of-fact about my depression, and sometimes tried to change my actions by shaming me. She was NOT what I needed. I want my therapist to be more accepting, more open to being my partner in ideas of ways for me to improve, etc. So, you shoul ask yourself what you want out of therapy. Also, be aware that if you think you need medication, you will need to see a psychiatrist, but those people are in short supply where I am and often don't want to do the sessions, just prescribe drugs.
Hope this helped!
Ellen