Doing surveys online. I use http://www.cashbackresearch.com as my main base site and sign up on other survey sites through it. If you are consistent with it, you will earn money. I’ve already earned $75 and they pay you when you have at least $30 through Paypal or you can choose gift cards, instead.
Use coupons and rebates to save money and then use the money you save for whatever you need the extra money for. If you also make this a habit, you will consistently have more money. I use http://www.southernsavers.com as my main site to find out what’s available.
There are billions of dollars that are owed to people, but you won’t know unless you check. Go to NAUPA, their website is: http://www.unclaimed.org. Most people find something! So far, I’ve sent claims for $389.65 total from 3 different claims!
Go through your “stuff” and clean it out, you can sell things on ebay.com or other auction sites or have an old-fashioned yard sale. Most people have something they don’t use anymore and can sell.
If you have a talent for DIY projects, crafts, anything handmade, you could go on http://www.etsy.com to sell them.
Find a good Goodwill and/or a Salvation Army and/or a good consignment shop in your area. Always check them, before going to a Walmart or other Discount Stores or Department Stores. If you make this a habit, you can really save a lot and also earn by buying items that you can resell online. Make sure to do your research on the auction sites, before you buy to get an idea what you can get for the item. (For example: what items are worth money and how to check them for proof of who made them, etc.)