A good source of sponsors for beginners to build up a portfolio and some experience is local businesses. Identify businesses in your niche who are located near you. If they can't afford to pay you, you may want to explore some form of bartering. Once you have some experience under your belt, look at partnering with marketing and PR agencies. Form a good relationship with one (or a few), do consistently excellent work, and then you'll get more work from them in the future.

Similarly, sponsorship market sites such as Cooperatize, PayPerPost, Sponsored Reviews, and Tomoson can help you find sponsors by performing a middleman function, leaving you to concentrate on the writing. For additional resources on where and how to pick up more sponsors, A Beautiful Exchange offers a number of tips for working with media companies and pitching companies directly to build a business relationship and make money online.