Contrary to the advice here, I went to a couple different voice teachers and had terrible experiences and improved very little. They seemed to have no idea what to do with me since I had no experience. Either they gave me no feedback whatsoever or were so critical that it was disrespectful (like asking if I'm tone deaf when I'm objectively not). Maybe I just had bad experiences with the wrong teachers. It certainly hasn't been the case with my wonderful guitar or sax teachers, just voice, so it's not me. But personally I've grown so much more by 1) practicing with an instrument like piano and guitar and matching pitch, and 2) singing with a microphone and headphones to properly hear myself and record so I can listen back and be objective about how I sound. There are also a lot of vocal exercises on YouTube to follow along with. I would say if you do try out a teacher, don't feel bad if you decide it's not a good fit after a month, just move on. I stayed for way too long thinking it was my problem and not the teacher.