The travel guides we use are, surprise, surprise, the Lonely Planet and the very reliable Bradt Guides. For African countries and the Middle East we definitely prefer the latter, since it is much more detailed.
Trip Advisor has become a source as well, even though it revealed quite unreliable. Some evaluations are completely misleading. A few times we ended up in real dumps recommended eloquently by supposed visitors. We are more and more cautious using this platform.
Forums are another important source of information, often more accurate and closer to reality than any travel guide can be. The Lonely Planet ThornTree Forum is probably the most active & reliable exchange of travel experiences.