Flying in Europe, I place a circle on the map (using the FMC) to mark terrain above 10,000' - and on entering the circle give a quick brief on depressurization, initial safe descent altitude and escape path. I also place a circle around Mt Blanc, if that is in the area.
If I am keen I use the FMC to calculate Critical points to company bases, in case of a diversion required, but not necessarily to the nearest airport.
I check en-route weather forecasts if there is a chance of weather which would affect an emergency diversion (fog or thunderstorms).
For political situational awareness, if I am flying over areas in Europe with low levels of civil stability, I download the travel advice from the Foreign Office website for those countries, and print them out to read en-route, which might affect, say, a medical diversion.
Serbia travel advice
There is a reciprocal healthcare agreement for British nationals, which entitles you to free treatment in Serbia for genuine emergencies. However, the health system in all parts of Serbia is suffering from widespread shortage of medicines and other essentials. Payment in cash is normally required for treatment and you should take out comprehensive travel insurance to cover medical evacuation.