Does the foreign national already have work authorization in the U.S.?
This is the most important question. You cannot discriminate in the recruitment process by asking if an individual is foreign or U.S. born. However, you may ask "Will you now or in the future need a work visa or authorization to work in the U.S.?" Many times a foreign national already has an employment authorization card or a green card which allows the foreign national to work in the U.S. Often, however, the foreign national is only authorized to work for a specific employer performing a certain job. If that is the case, your company will still need to sponsor the foreign national which takes us to the next step:
If the foreign national does not have work authorization, does your company allow sponsorhip of visas for foreign nationals?
Considerations will include: the cost of hiring a foreign national temporarily and maybe even permanently. In most cases the employer is required to pay at least a portion of the visa petition fees and sometimes even a plane ticket back to the foreign national's home country. Often the the foreign national will request sponsorship by the company for permanent residence (green card). Dependent family members will be accompanying the employee in many cases. Are you willing to pay the cost of their visas or green cards too? On the flip side, if the company chooses not to sponsor the foreign national for a green card then you risk the employee leaving. Often there is a cap on the amount of time a foreign national may work on a specific type of visa. Finally, there are employer compliance Issues to take into consideration. By hiring foreign nationals you could face civil or criminal fines if the company violates immigration and/or labor laws.
If your company decides to hire a foreign national, consult with an immigration lawyer
Do not assume that you can prepare the paperwork on your own. Immigration law is complicated and often in flux. Speak with a qualified immigration attorney. You will need to provide the attorney with the following documents of the applicant: Resume, Educational Documents, Job Title, Job Description, Salary, and Evidence of Current Visa Status (if any). Do not assume that just because you are convinced that this candidate is the right person for the job--that USCIS agrees. Each foreign national must qualify for the requisite visa category based on USCIS standards, not yours. Therefore, education and previous experience may dictate whether the visa petition will be approved.
Timing for Visa Issuance
If your company needs to sponsor a foreign national, do not assume that s/he will get the visa immediately. Employment visa petitions can take weeks or even months to receive a decision. Then, if the foreign national is outside of the U.S. s/he will also need a visa in order to enter the U.S. Set a realistic start date taking into consideration possible delays with the U.S. Department of Labor, USCIS, and U.S. embassy.