Finding a therapist can be such an emotionally wrenching process. To begin with, you are experiencing something in your life that you need help with, which is in itself a vulnerable place to be. Be good to yourself, take your time, and know that this is a hard process for everyone, even for therapists!
If you have a referral, that is if someone has recommended a therapist to you who you are willing to try out, that is often the best place to start. Ask around. You may be surprised, and a recommendation may come to you from an unexpected source. Sometimes these interpersonal connections have a way of delivering to you exactly what you need.
Once you have visited a therapist, actually walked into their consulting room and met them -- congratulations! -- that is often the hardest part and requires a great deal of courage. At that point the important thing is how you feel that you fit with this person. Are you comfortable talking with them? Can you imagine sharing with them uncomfortable parts of your life? Is something new happening, even if you can't consciously identify it, some feeling that you are now on a different path? Often these subjective hunches are indicators from the unconscious parts of ourselves that we are on the right track. From just a few initial sessions you can generally tell if this will be a good working relationship for you that will support and further your process of healing and development.
I wish you luck, strength, and courage as you embark upon your journey.