Every day students come up to me and say, “I've got an audition coming up. Here's my music; I have no idea if I marked everything correctly!” I understand the confusion. Every pianist is different, we have our own marking preferences, and if you're not the greatest music-reader then so much of what's on the page looks like gibberish anyway. But there are some guidelines that apply to nearly every pianist in nearly every audition.

Don't just mark where you want to start singing; mark where or how you want the pianist to start playing. This could mean indicating the song's intro, putting down what pitch to play so you have your opening note, playing a bell tone (which isn't always the same as playing your opening pitch!), or writing down that I should start at the same time you sing.
ut down where you want the pianist to stop playing. I often encounter music with long endings and I have no clue if the singer wants all of it or really wants me to cut off sooner. Even if you want that long extended ending, best mark down where you want to end anyway just to be on the safe side.
Mark any cuts. This should be obvious and most singers come in with this done, but double check to make sure the cuts actually work. I've seen some music where the cut adds another count to a measure by mistake. Be careful!

That's all for now! Look for Part 2 in a couple weeks.