Now that my husband is finally receiving a regular paycheck again that provides us enough to live on (and not just scrounge out an existence), we have re-instituted our 10% fund, our "paying ourselves first" fund. Even if you don't make a lot of money (which we don't), 10% of your income every month--or whatever percentage you can manage--adds up more quickly than you think. The trick is to do it as soon as you get your paycheck, then forget it's there. After a while it provides a nice cushion for emergencies or safe investments like CDs or money market accounts. If the term "pay yourself first" doesn't hook you, then think of it as insurance for a rainy day--and you get all of the money back.
Here are some great resources on the topic:
About.Com- Investing for Beginners
"When you set down to pay your bills, the first check you write should be to yourself. Decide on an amount you can commit to for at least six months and immediately pay that 'bill.'"
"It’s important to understand that this money should be untouchable. It’s a good idea to make “the payment” part as painless as possible by automating your savings (talk to your banker) so that you never see a single peso. Try to set up two bank accounts – one for your expenses and one for long-term savings."