Once you have found the right international qualified professional for your company, you can then officially offer them the post and agree when they will actually start work. It might be helpful to the new recruit to provide the work contract in English or to discuss certain points with them. When signing the work contract, tell your new recruit about the legal aspects, for example the statutory insurance and taxation in Germany. These arrangements may be quite different in their country of origin. This is why you should appoint a fixed contact person for queries. You can find out more about "Support for administrative and legal formalities" here.
Important note: A qualified professional from a non-EU country is allowed (subject to certain conditions) to sign a work contract before they obtain a visa. Often, a work contract is a prerequisite for obtaining a work visa and must generally be submitted to the respective German embassy or foreigners’ authority. You can note in your work contract that it will only take effect once a valid visa has been obtained. You can find out more about this in “Entering and working in Germany".
Federal Employment Agency (BA)
Information on admission to the labour market (German, English)