I'm not in a good mood today having been turned away from the Consulate of Gabon for a second time. There's a long list of things needed to obtain a visa, including confirmed ticket, original hotel booking, letter of invitation, insurance cover, letter from employer telling you to go and one which many economists (but not accountants) might have difficulty fulfilling, 'justification of professional activity'. These are the most difficult entry requirements I have come across anywhere, except perhaps Kuwait back in 1987. My advice is to minimise the hassle and use a visa service, and expect the requirements to be interpretted to the letter!
I guess this is not very different from what a lot of our readers have to go through to visit an EU country. I now know how you all feel!