Government contract opportunities get passed by because a lot of vendors believe that there is one central website that caters to contracting opportunities, which is Federal Business Opportunities. Federal Business Opportunities, or FBO is the most popular site that receives a large portion of online traffic from vendors. In addition to FBO government agencies also post bid opportunities internally. Some of the opportunities cater to subcontractor bids as well. Here is a list of the top five websites that I have personally utilized that will assist you in your success.
Of course in working with the federal government there is a requirement that you have completed all of your registrations through SAM, Dun & Bradstreet, and the IRS.