Yo! I have been there and it was fab!
I would suggest a thin sleeping bag would be fine, its quite warm and humid all the time, but definately a mosquito net aswell - be really careful with the mosquitoes, they're everywhere.
In Accra I remember seeing only a few single white people around. I was there with a group so I always felt pretty safe, and even walking around on my own was fine. I wouldn't advise it at night though, mainly because nowhere is really well lit and its hard to find your way around.
If you're travelling around then buses are pretty slow between places... pretty much everything seems to go through Accra. I recommend a place called Kokrobite, which has a lovely little resort called Big Millies Backyard - its West of Accra and on the coast, the beaches are beautiful, awesome food and the culture is rife... I could have stayed there for ages. I never headed up there myself but apparently in the North of the country they do wildlife safaris and what not so that might be worth checking out. Wherever you go though be prepared to be stopped by police and "border control". Always carry your passport and documents because if you don't then they'll ask for money to get through... this happened to me in the middle of the country!
Generally the people are wonderfully friendly and welcoming and I had such a good time, I say go for it

And also... its about 16000 cedis to the British pound, so you can become a millionaire over night, haha.