How long did it take you to see noticible improvements?
The thing is I wasn't able to pull off an Axl Rose within a few weeks or months. It took years. I have two recordings of myself doing the song "Patience". One was recorded about 6 years ago, the other was recorded about 6 months ago. At the end of the song on the old recording when I'm trying to hit the high notes, it truly sounds like crap. You can really hear me struggling with it. On the new recording, you can hear me belting it out, and doing a fantastic job at it.
My old recordings of myself sound absolutely nothing like I do now. There's no quality, passion, range, nor vibrato in them. They all sound very nasal. The time that I made the biggest improvement was when I was singing on an almost daily basis. Comparing the two recording is like day and night.
One thing you should keep in mind when trying to be like the CD is that they have truly wonderful studio technology that can make the voice sound better
This has nothing to do with trying to match your voice with what you hear on the CD. No singer is perfect, but one can usually tell a decent singer from a lousy one. Live recordings are excellent for finding out if a singer is only good in the studio. Also, don't forget that they usually do multiple takes in the studio, and can take parts from each take to make one really good one.
Also, there's some singers and songs that you're just not going to be able to pull off very well. You might be able to hit all the notes, but it just won't sound that great with you singing it. I can sing Bon Jovi tunes, but my voice just doesn't work very well with his music. A raspy raunchy voice doesn't sound that good singing "Bed of Roses".
Just a piece of advice: keep your old recordings to see the progress you're making.