If you have a checking account, review your last month's entries into your checkbook. I never wrote what the cash was for. Twenty dollars here, forty dollars there, it added up to hundreds of dollars every month. You may also try to reduce your debt by reducing the rates on your credit cards and loans. The Financial Center has many links to these resources.
Saving starts with discipline.
Review your expenses, make a budget, stick to it, and have the money that you want to invest deposited directly into the investments from your payroll or bank account.