Very Short Question as not sure if you are currently in India or USA as the process to start a new company from both these locations will be different.

If you are in US and are eligible to register a company then:

1. Simply go ahead and register either an LLC or an INC as per your requirement.
2. Obtain an EIN (Employer Identification Number) for your firm.
3. Once you have the company registered, you need to obtain proper Insurance for your company which includes but not limited to General liability, Auto, Workers Comp, Employers liability, Professional Liability (e&o) and Excess Liability depending on the clients you are going to cater.
4. By now you must have decided your Industry you would be recruiting for. (Example: IT, Manufacturing, Medical, Financial/Accounting etc)
5. If you have an idea of doing the Business Development to reach a new client and propose your new staffing services then do it yourself or if you feel the need then don’t hesitate to hire a professional Business Development person who can better portray your services to the client in more professional manner.
6. Now as you have new client accounts, just start recruiting yourself or hire 1 or 2 recruiters to start with to source the profiles for your client requirements. Once you feel the need you can always increase your recruiters depending on the flow of requirements from your clients.
7. Setup the interviews, followup with candidates and just count your placements.
8. If you have achieved all above points by now then you are already a revenue generating staffing company and you just now need to generate the invoice to your clients and see the funds coming.

If you are in INDIA and thinking of getting into US Staffing business then:

1. Register a company in USA as LLC firm.
2. You can put the US firm as the branch office of your India office or can be an independent office. Either way you need to find out a local USA based business address. You can try Virtual Offices or Registered Agents to help with that.
3. Get an EIN (Employer Identification Number) for your company and TIN (Taxpayer Identification Number) for yourself. Both will be required for Tax filing purpose.
4. Get a bank account opened in any Bank in USA
5. Plan your strategies as how you would like to deal with your clients. You can go and try to obtain some End Clients or you can work as a Sub-Contractor company on C2C with any existing US Staffing Firm.
6. Depending on the way you would like to work, you need to go and get an Insurance for your US LLC company.
7. And from here you just need to follow all the steps from Point 3 to 8 in above given answer.

There can be some other one or two legal formalities required as per your location.

Best of Luck to your new business and In case of any further help or info you can always reach me at nash@globalgids.com