The federal government has goals of the type of businesses they want to do business with. If they don't meet the goals, then they have to answer to the Congress as to how they plan to meet the goals. The US federal government must do business with businesses in the following categories.
Federal_Government_Contracts.html
The GSA (General Service Administration) also has socioeconomic business goals of what type of businesses they want to do business with a year.
Socioeconomic_Business_Goals_for_GSA.html
If you want to do business with the government, the first thing to do is to register with the Central Contractor Registration or CCR. All firms wanting to do business with the government are required to register before the contract or task order can be awarded.
How_to_Do_Business_with_the_Government.html
There are three basic types of Government contracts based on dollar thresholds. Small government contracts are the easiest to obtain because you would not have to make big presentations or compete with other contractors.
Government_Contracts.html