Federal jobs, go to fbo.gov. You have to register you business and keep your registration current. Hope you take creditcards because they are doing away with checks.
You may be eligible for preference hiring like small business, minority owned, etc. All that info is available on the website. Those only apply for jobs up to $100k
For larger projects like new construction and major renovation, you will have to work with a general contractor. The govt will deal only with the GC and the GC deals with his/her subs.
When doing govt work, there's a bit more paper work involved like submittials, training, and O&M manuals so you should add some for that.
And the big one is you will be required to pay your peeps Davis-Bacon wages and there's a butt load of rules and regs and more paper work that will be needed to add to your costs
