The biggest roadblock I've found to getting a good vocal out of SV is using one of the "lite/demo" databases. When I first tried SV it was very disappointing.

I took a chance and purchased the full SV and a couple of the voice databases. That made a significant difference in the results.

Also, if there's one secret to getting a good vocal that sounds real it is this. Learn how to use the vocal pitch line. That gives you the inflections you need to make it sound more like a human singer and less like a synth.
In SV, you can actually draw the line manually which is really useful. Not even Melodyne lets you manually draw the pitch line.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.