A visa must be obtained before travel. The standard visa costs around 50€ from Europe, £20 from the UK and around 160$ from the USA. Multiple entry and long term visas for up to 2 years are available.
All inbound travelers who are at least 9 months old must be vaccinated against yellow fever to get into the country. Get the vaccination and an original certificate of vaccination as proof to submit with the visa application.
Don't stop with the yellow fever vaccination. The WHO recommends that anyone headed to Ghana be current on all routine vaccinations; those who aren't should be vaccinated at least four to six weeks before departure to develop full immunity. Routine vaccinations include measles/mumps/rubella (MMR), diphtheria/pertussis/tetanus (DPT), poliovirus, chicken pox and influenza. The WHO also recommends vaccinations for hepatitis A, malaria and typhoid, as well as hepatitis B, meningitis, cholera and rabies in certain circumstances.
The official currency of the Republic of Ghana is the cedi. Currency can be exchanged at foreign exchange facilities at major airports, at forex bureaus and at some commercial banks in the country. Travelers checks may be accepted at some banks. American Express, Diner's Club and Visa are the most commonly accepted credit cards in Ghana, but the State Department advises against using credit cards in Ghana due to a growing problem with credit card fraud in the country. If you're going to risk it, remember to tell your card issuer about your travel plans so they don't freeze your account due to suspicious usage.
Health facilities in the Republic of Ghana are limited. Carry plenty of any prescription and over-the-counter medications, an extra pair of glasses and everything else important. Foreign health insurance may not be accepted by healthcare providers in Ghana. Although TouringGhana.com notes that the tap water in the country's major cities is hygienic, it still recommends drinking bottled water.