I just thought I'd post this, because it's an issue that many artists here overlook.
Warming up the vocal cords.
Perhaps you've heard it on your own songs, I know I've heard it on mine: the second verse sounds more full and controlled than the first. Perhaps the third verse sounds hotter than the second. This is because, as many singers learn early on, your vocals are not going to sound their best until they warm up. Your control over your vocal tones increases after a few verses.
So, what I would recommend is that artists be sure to run through some practice sessions on each song at least once, perhaps twice, before actually recording. You'll benefit from vocal consistency, and your song will improve sound-wise as a result.
Any thoughts/comments?