Best advice?
I can't think of anything that's going to easily fix someone's singing problems, specially if singing lessons seem to be what they need. So you can try the suggestions made by others. They will help by warming up the vocal chords and giving them a bit of exercise. The tricky thing with singing is that it's something people do naturally, so often they don't think about having lessons. Then they develop a particular way of singing (e.g. through their nose), which become ingrained, and they can't get out of that habit. Good contemporary vocal teachers will show you how to choose the sound you want, Singing nasally then becomes a choice, not a limitation.