Obtaining a visa for Giunea-Bissau can be very difficult. For one, there are no clear procedures on how to get one, not helped by the fact that there are no Guinea-Bissau embassies in the US. If you are up for the challenge, there are two options: you can either obtain a visa from the Guinean embassy in Portugal (Lisbon) or get a letter of invitation which allows you to arrange for a visa on arrival in Bissau. The second option is much more expensive than the first, and since there is no set policy regarding visa applications upon arrival, it is much safer to go through LIsbon. The Guinean embassy in Portugal may be able to process your tourist visa within two to three hours (the same day as your application), but it is smarter to call ahead and confirm arrangements before making your travel plans.
Health and Safety
Having a comprehensive health and travel insurance policy is a must. In addition to a yellow fever vaccination, it is also advisable to have immunization against other diseases such as hepatitis A, typhoid fever and tetanus. Anti-malarial medications are highly recommended, as well as precautions against tuberculosis and epidemics like meningococcal disease.
Guinea-Bissau still has a high level of instability due to the recently concluded civil war and continuous political turmoil. Always check travel warnings from your government before planning a trip to this side of Africa. Petty and violent crimes are prevalent, so always be vigilant and practice caution in whatever you do.