(wheww.. when the subject is the singing voice I can contribute much more than in the subject of folk !) :)
Very short recommendation: don´t loose your time practizing alone, go to a good, CLASSICAL teacher. Alice has said it all. Why not a popular singer who teaches ? Because classical singers have a much deeper knowledge and experience in voice training. Once you achieve some important goals (extending the range is only one), you may go to any popular teacher you may like.
My experience ? Went to my first choir as a bass at age 46, my director reclassified me as a baritone, started serious study at 49, now I'm a tenor and my range is from low G to high Bflat (in rainy days some of the famous high C), I mean two octaves and 3 semitones, and am enjoying solo performances too, at age 53, and improving. And my voice is nothing special. And I´m a smoker.
(You know, the best age for a well educated singer is beyond 60)
Never force your voice, never sing in open air, keep improving slowly with a teacher listening to you.
Best of luck and good work! - Andrés