One of the toughest issues with new singers is getting their vocal to cut through the mix or how to sound clearer with vocals.  While some of this is the sound mans issue.  There is plenty that is up to the singer.  One of the things that i always suggest right away is to get used to singing with your mouth all the way up on the mic.  Too many rookie singers hold it so far away that their vocal cannot get loud enough to go over the other instruments.  Another issue is where they are getting their breath support from.  They are either getting it from their diaphragm or their lungs.  A good singer will take breaths from their diaphragm.