In Ethiopia, the main thing to be conscious of safety wise is petty theft, opportunistic snatches of phones, jewellery, money. As long as you take sensible precautions, there are not really many other threats to foreigners. Therefore, my simple advice is to not wear expensive jewellery (or even jewellery that looks expensive) – I tuck my necklace into my top when I’m walking to/from work. Keep your phone out of sight. Put money in zipped or tight pockets. Be conscious of the clothes that you wear.