If you're merely trying to reproduce what some star had on his/her CD, that's fine, I suppose. But if you're making the song your own, and if (as not everybody is) you want to make the words and story line, if any, clear, you need to look to the e-nun-ci-a-tion.
For instance, in A Bird in a Gilded Cage", you need to be sure the final consonants are CLEAR, CLEAR, CLEAR! Thus "For her beauty was sold for an old man's gold" becomes "For her beau-ty was sooo l D for an oooo l D man's gooo l D-----She's a bird in a giiil-ded cage!" "Gilded" is not "gillllllllld-ed" but "giiiiii L ded", holding the I and sort of sliding over the L.
The held note of sold or old or gold should not be on the "L", as might be tempting, but rather on the "O", and the "L" is just touched on, and the "D" is almost "Duh". "Win" is not "Winnnnnnnn", but "Wiiiin", with the consonant just prominent enough not to get lost. "Light" should be "Liiiiiigh-t".
I came from a part of the country where in speech we pronounced a final R as "ARRR" or "ERRR". I resented the advice of singing-enunciation books that a final "R" not be pronounced, as being stuck up or English-regional or something. And yet, after a long time of listening to really good singers in various genres--take for instance Sinatra--I realized that the clear (and non-regional)singing of excellent singers was often because they followed these what you might call formal rules, but without posturing about it. Today, a final R in my singing (I discovered recently) come out as "-eah" with a sort of R overtone to it. "Here" is closer to "heah", although not exactly. And I, at least, don't think it sounds mannered or stuck up.