It might seem counter-intuitive to give when you don't have much, but I firmly believe that God helps those who help others.
Life isn't about just getting through. It's about having a rich and full experience, and being happy. Helping others is a great way to make yourself and others happy, even when you have to pinch pennies.
Besides, you don't have to give money. Share what you have--take a plate of cookies to someone, give away (instead of throwing away) or donate used but still useable items and broken but fixable items (try Craigslist, or give it to DI or Savers--they even sometimes give you a 20% off coupon when you donate!), invite someone over to dinner. Or share what you do--mow someone's lawn, mend or alter clothing, teach a skill you know, tutor, share your talents. Or share what you are--write a note, be a friend, make a phone call.
Being generous is not just about sharing our money. It's also about sharing our time, talents, skills, and other resources to make other people's lives richer, fuller, happier. And it does the same for us.