Talent is something you are born with that can make it easier to acquire a skill like singing. Most of the people I have seen who think they are terrible singers are the ones who are not skilled at matching pitches. The good news is that the ability to match pitches correctly is a brain skill that can be learned. The rest of learning to sing is establishing correct coordination of the "singing muscles" so that what comes out is what you planned.
Q. If I start lessons now, when will I know how to sing/act/have a better speaking voice?
Like all physical skills, your innate ability, how you practice, and how much you practice will determine the speed with which you improve. Having a skilled instructor is critical to this process.
Q. Will I have to sing scales?
Yes, you will have to learn many patterns to train your voice to sing properly. I often compare singing to tennis in that you can become somewhat better by playing game after game, but you will only truly improve when you break it down and work on your forehand, backhand, overall strength and aerobic conditioning, etc.
Q. Will I have to learn a foreign language?
No, but if you want to advance the fastest, you will be open to singing languages with which your brain is not already familiar. The best description is that singing in a foreign language will make an end run around a lot of bad muscle coordination present in your native language.
Q. I have an audition in 4 weeks - HELP!
In that timeframe, you will be able to learn notes and style for a selected piece. Actually getting new technique into your voice such that it comes out at an audition takes longer. Allow 3 to 4 months or more to properly prepare for an audition. The same can be expected to retrain a speaking voice or for acting lessons.
Q. How can I be a good singer, speaker, or actor?
Take lessons with a good teacher.
Practice carefully and correctly.
Take good care of your voice, both speaking and singing.
Listen to good singing, speaking, and acting.
*Courtesy of Karl Resnik
Q. How can I get the most for my money?
For the fastest results, do only the voice exercises you are given and refrain from singing anything else until you get the green light.
While you are studying, performing in shows constantly will slow your progression.
Bring a pencil to every session.
Have printed music for every session.
With advance notice, attending other students' lessons will help you to learn even more.
Video your lessons - you’d be surprised how much you learn by watching yourself!