Scriabin,
When you're first starting out, trial and error is about the only way most people have available. After a while, you start to learn the characteristics of each mic in your locker and you can pretty much narrow it down to 2 or three mics to try when you hear someone's voice. I guess "experience" is as good a word as any.
Part of the problem lies in the fact that almost any condenser mic sounds wonderful the first time you hear it against an average dynamic mic, but it's only after a while that many new recordists will start to hear the flaws in many condenser mics, like screechy top end peaks (which new people initially hear as "more detailed").
Time, critical listen, experience, and detachment will all help you hear what's really happening. Compare your vocal tracks to professional cuts that you like to hear the differences, and then experiment with all the mics you have to see if you can get closer to the sounds you really like.
You'll know you're getting closer when you listen to a record and instead of hearing the music, your ear will pick out a key part and you'll think, "Wow, how'd they do that?". Even closer is when you hear a new record, and you KNOW how they did that.
When I listen to a CD (that people want to sound similar to), I can usually figure out what mics I'll need to duplicate the vocal sounds, the drum miking and placement, eq, compression, and bass and guitar techniques in about 2 minutes, but that's based on about 40 years of doing this stuff. The most difficult problem you'll have is losing your preconceptions and just listening.
As far as what mic is best for your voice, here's a trick you can use to save some bucks and narrow things down quicker than the trial and error method:
Book some time in a local studio and make sure the studio has a good range of mic choices. IF you can, try to book "down time" (time when the studio isn't normally busy) at a reduced rate.
Have the engineer cut about one minute each of you singing into every vocal mic they have. Make sure the engineer keeps track of which mic goes with which track. Have the engineer burn a CD of all the tracks, and tell him to mix up the order, but make a key of which mic is on which track. DON'T LOOK at the sheet!!. Take the CD and the folded key sheet home. Put the "key" sheet in a drawer without looking at it.
Take 3 sheets of blank paper and put track numbers on them. Listen to the CD and pick out which tracks sound best on your voice and mark those choices in order on one of the blank sheets. Fold that sheet up and put it away.
Do the same thing about a week or more later, mark your selections, fold and put that sheet away, too. Don't look at the key sheet or the previous sheet.
Wait at least another week and do the listening test again, and mark your selections. Now go get the other sheets, and the key sheet. Did you find one track that you consistently liked in every test? Get the "key" sheet and that's the mic you want to get, or at least find something similar.
