For travelling its good to have a travel guide. In this way you get a lot of information about the country and the people living there. Also you can find cheap guesthouses, hotels and buses.
For germany there is only one travel guide:
"Ghana - praktisches Reisehandbuch für die Goldküste Westafrikas Jojo Cobbinah" Peter Meyer Verlag (sehr zu empfehlen wenn man nicht immer alles übersetzen will ;)
But there are more english ones which are also really good and give you a lot of information.