You have to look at your voice in three parts:
1) As a muscle and part of your body: You need to work it out. It needs exercise, proper nutrition, possibly supplementation, and a healthy lifestyle. So many things can effect your voice for the positive and the negative. Although smoking can speed up the maturing of your chords, in the long run, you should quit to avoid hardening, scar tissue, and cancer. Then there are your lungs; take care of them. Your diaphragm should be free to move for breathing as well. You need to have a good rib swing, so no rib injuries or over training in the oblique, abs, trapezius, or other muscles that may constrict breathing while giving you positive aesthetic results. Hydration, iron, and many other vitamins and minerals also play a part. AND you need to exercise it. Sing often. Have a doctor that knows singers (not just about them, but knows what it takes to keep you healthy in an emergency, even if you do it recreationally).
2) As an instrument: Very rarely are people born with safe placement or skills to survive injury, exhaustion, or over training. You should always take voice lessons to learn about placement of the tone, tongue placement, breath placement, soft pallet, among other placement methodologies. Also, you need to learn classical technique, not so you can become a classical signer (necessarily), but so you can get yourself out of a jam in the event that your tired or injured. Look at your voice teacher like a trainer. They give you proper form and direction when using your voice. Even going to class once a month is better than nothing at all. Be reminded of the risks of powering through a song, or risky habits (too many glottal rubs or stops, placements that can cause strain, or risk of TMJ.
3) As a performer: Once you have all of that, health and training, learn to play and express with your voice. My ‘50 Times’ rule applies to this. Sing it straight, with no embellishments 50 times. Then you will know how it is supposed to be sung with your instrument. Play and express.
WHAT YOU DON’T NEED: I’m always wary of those who say you need to do x in 6 months, then you are allowed to do y, and you won’t get to z until so many years. This is a financial trick by teachers. Yes, we all need to make a buck, but our buck is valuable. Get what you need, and move on. A good teacher should be able to tell you what you need help with and what to do on your own to excel the process. There is no real timeline, but there is also only so much a teacher can do in an hour (don’t expect miracles).