Where you want to live depends on your budget. The expat areas are Cantonments, Labone, Osu, Ridge, Airport Residential and East Legon.
You need to be prepared to pay $2500+ for a two-bedroomed apartment and you will have to pay at least a year's rent up front. You will be able to get much cheaper accommodation if you are prepared to live further out of Accra but you will still have to pay the rent for the year