I am fishing in the Maryland Division of the Weekend Bassmasters series this year as a Co-angler. All you have to do to fish in the Bassmasters Weekend series is pay all of the membership fees and entry fees. You can be a co-angler or boater. Here is the link to the website:
http://www.americanbassanglers.com/BWS/
If you are in Northern Virginia you would probably want to fish the Maryland division because all of the tournaments are on the Potomac. The Virginia division is better suited to people that live in the southern or western part of the state. The Virginia tournaments are on Kerr, Anna, James and Smith Mountain.
Memberships:
Join Bass $25
Join ABA $25
Tournament fees:
Boater $200 (Must have $300,000 liability insurance that allows fishing in tournaments)
Coangler $100 (Should expect to pay 1/2 gas and oil)
Linking is where you find a boater that has registered in the tournament and link with them. That guarantees that you will both fish in the tournament. ABA is trying to ensure that they have exactly the same number of boaters and coanglers. If they have too many coanglers, the ones that do not have a link don't get to fish. If they have too many boaters the last ones to sign up without a link will be forced to share one of their boats and each have half a day to control the boat.
Winning tournAments can help but isn't necessary to be sponsored. I know of multiple people that have not won so much as a club tournament and are sponsored. These people are called "Patch Collectors" in our area. What companies want is someone that can sell their product. You need to find small companies and volunteer your time to try and sell their products at fishing shows or even drive around to tackleshops and get them to sell your sponsors products. One guy I know pimps his sponsors products on a Facebook page. If you can demonstrate that you can sell their product, they may give you a sponsor shirt, free baits to use or give away or maybe just a discounted price on their products.