Trial and error is my favorite place to start! I'm not aware of any sites with exactly what you're looking for but i'm sure people will put up some good links.
I like to think less is more though as a general rule. It's natural to put on a fat verb cause it's a new thing(if you're beginning to mix for the first time) but try and add only enough effects to add a little texture. I use Waves plugs with subtle reverbs and a multi tap delay is good as well, especially if the delay allows you to input a tempo. If not, seek out a conversion chart cause a delay that's in time sounds really nice.
My first suggestion is liberal use of the effects bypass button. I’ve spent extended periods working on just the right effect only to find that the piece sounded better with effects bypassed. Humbling.
Another vocal effect is the “harmonic exciter” in Izotope Ozone. Used sparingly(!) it adds punch to vocals.
Mixing vocals is something that can be a career long learning experience.
Try googling the term "mixing vocals" (including the quotation marks and you'll get some good reading material that's available on the web.
And as was mentioned before, with a well recorded, well performed vocal less tweaking is often times more.
B.