Here is one thing never to do when asking for more money. Never ask for it nor justify it because of your need. If you work for a for-profit entity, as many of us do, your need is completely irrelevant. While I can personally be hugely empathetic to your financial needs and hardships, I can not justify increasing your compensation because of them that is unfair to the company and to any coworker who puts in the same effort but walks away with less.