Throughout my travels, I’ve discovered I don’t need a lot. When I’m restricted by weight on a flight or because I’m backpacking, the following items take priority (even over clothes!):
Quality camera and gorilla tripod
Sarong or large scarf (they have so many uses e.g. towel, picnic blanket, conservative headscarf, winter warmer, light beachwear, wrapping for precious items, bed sheet etc.)
Sunscreen, moisturiser and lip balm
Kindle
Earplugs and headphones
Thongs / flip-flops
Phone (for keeping notes, accessing social media, e-research, maps, music and a torch light)