If you do somebody a favor, you offer them some sort of help.
"Lay an egg" means for someone to embarrass or disappoint with their performance.
"Cream of the crop" is another creative way of saying you're best of the bunch.
It's yours to lose means you'll probably have it unless you do something really stupid.
To die hard is to die in the hard way, not ceasing to be easily.
Whenever people ask you to "think big", they mean for you to be ambitious.