Hey,
I would do two things with a pitch
reference. Piano/keyboard would be good.
One is pick a note that's very comfortable to sing. Not too low, not too high.
Now sing it and hold it. While you're holding it listen to it. What's wrong? Weak?
Change how you're singing the note as you hold it.
Make it fuller, stronger, rounder etc. Try to impersonate a famous tenor or sinatra with your tone.
Put your hand on your gut. Are you tensing? Supporting a smooth constant flow of air? You should be.
Two is an extension one, kinda.
Pick the note and do as above but quickly and just over, say, four seconds.
If the note is C, Go like this.
C---D---
C---E---
C---F---
C---G---
C---A---
C---B---
C---
C---
C
The aim here is to hit the correct pitch each time. Don't worry if you have to glide into it or
find the note. As long as you get there in the end.
Do this regularly, especially before singing.
Think of your voice now as someone fumbling around on a violin. You want to go from that to someone confidently striking a piano key. What a kick ass analogy, right?
These two things should improve your pitch accuracy, your confidence, and the strength with which you sing.
Without even thinking about it, you're likely to see a big improvement fairly quickly.