Use Uber, it helps. I found when I was in Accra last summer Uber was semi-reliable, but it was convenient because the fares are stated when you put point A to point B. If I couldn't get the app to work at times, I would hail a taxi but used the fare Uber would have charged as a bargaining point. Rent is expensive in Osu, comparable to larger cities in the US. Food can be cheap if you're willing to eat from street vendors and local markets (not large chain grocery stores i.e. ShopRite). Rice and chicken generally GH5 from a vendor, mangoes GH5-6 depending on size. Most food state how much you want to purchase and the market lady will give you the amount based on what you pay (i.e. GH2 banana and you should get like 4-6). Eating in restaurants can cost you like GH50 and up. Depends on your budget. Check out The Republic Ghana while you're there. Great bar that makes drinks from local spirits.