Sorry for the delay in answering.
If George (Amsterhammer) reads this, this topic might be another one to move to 'Other Topics' as it isn't specifically Joe related.
The short answer is yes, of course you can shape your voice. Depending on the tone of your voice and what key better suits it, that might dictate the music where it fits better, of course.
That said, you can adjust the instruments on certain songs to assist you.
I mean, if you listen to a lot of blues and what to sing that then you can ape some of the techniques you hear. If you have an 'ear' as said before it is relatively easy to do. But first get the confidence in your singing.
I've said it on here before and it doesn't bother me to tell again, but I really starting singing once I had mastered Barry Manilow! I don't do him now, of course (unless I really have had too much), but I still know all the words.
Mark Knopler was fun, but more like grunting of sorts. Hardest is Bon and I wouldn't even bother trying with Brian J. or Percy Plant. I hate having to ask the guys to drop a half tone for me, but it is better than it sounding crap. Still it does mean that they then have an another guitar on the stage and they love having that!
When you are singing it is important to know you have a bit of space for that extra gear, but if you are singing at your limit already there is nowhere to go, so you can't give it any tonal light and shade.
The way I view is that I can sing rock, which I consider the hardest to do for me (opera is a no go anyway), so after that I think I can develop it for anything else I m ight need. Thats the theory for me anyway.
Good luck. Mail me direct if you want to discuss it any further. Don't know if I can help but you never know.
No Hits, No Hype.......................Classic Rock Jan 2012