I sing. I used to play acoustic guitars in pubs and venues, get paid $100 a night or more, and play covers for 3 or 4 hours with a couple 10 minute breaks in between. I also write music and have a few albums on Amazon.com and iTunes.
Best advice I can give you is that it's just like any other instrument you practice, I sing with music in my car...if you're self conscious you'll keep the windows up, but if you really want to feel free you'll roll them down and belt it out on a country road or a crowded intersection. I remember one day I was sitting in my car singing to a Soundgarden song and when I got out of the car there was this guy that had been listening and looked at me, nodded respectfully, and said "dude your voice is awesome". I told him I wasn't aware that anyone was listening, he said "keep it up".
I still play weddings and stuff from time to time, and I sing and lead worship for the youth group in church. Just keep practicing and do like you do with drums.
Lessons are good, I've never had them, but I've heard they help tremendously.