If you can't find a local voice teacher (or can't afford their fees), online singing lessons online may be a convenient and economical option for you.
If you have a guideline or criteria in finding an in-person teacher, you should also use that in searching for an online singing course. First, define your goals. What style or genre of music do you want to sing? Will you be singing with or without microphones? Where will you be singing--church, bars/nightclubs, or with a musical theater?
There is a wide variety of online courses available. Your choice will depend on what you want to learn. With vocal techniques, some programs offer comprehensive education in music theory and history. Others focus more specifically on performance aspects, such as tone placement and resonance, stage presence, and emotional interpretation of songs.
An important thing worth considering is whether or not to use microphones and electronic amplifications. Some courses don't teach you how to project your voice without it. If you can sing and project without a microphone, it's not difficult to adjust to using one. The opposite, however, is not true. If you don't know how to project and the sound system fails, you have a problem!
The best online courses cost about the same as ten to twelve in-person lessons. They explains the principles and rational of the exercises demonstrated in the audio file which is included in the package. The package includes both guided audio lessons and text materials by the way. Email support is offered in some service. Two of the best programs are Singing Is Easy by Yvonne DeBandi and Singorama by Emily Mander.
The first few lessons should teach you the fundamentals of posture and breath support as well as how the human voice works and how to improve it. You will also learn a variety of warm-up exercises.
If you're eager to get to the fun stuff, you may be tempted to skip the "boring" parts, like the breathing exercises. That's not a good plan--you'll only be shortchanging yourself, and you won't get your money's worth from the course. Professional athletes can't play at their best if they skip the fundamentals, and it's the same concept with singing.
You're pretty much on your own with an online program. There are no pressures, no deadline and your only accountability is to yourself. This can be a good thing if you work well without close supervision or if you're honest to yourself. But when you run into problems, it can be a real challenge.
The main problem with all online singing courses is lack of support. The teacher can suggest alternate exercises for you if a particular one doesn't work for you.. that is, if you have an in-person lessons. That isn't possible with online singing lessons.
One more thing, with regards to feedback, you wont get immediate feedback on your progress or techniques. Because our ears are located so near our vocal tract, we hear our own voice transmitted through our skull and sinuses, not through air as a microphone or listener would receive it.
Make an audio recording of yourself and play it back. That's one way, if not the only way to hear yourself as others do. Buy doing this, you can compare the audio examples in the lessons with your sound. The only issue is that it can be difficult to objectively judge your own voice.
You will get greater benefit out of singing lessons online if you are honest with yourself about the areas that you need to improve.