Don't take tools you will moslt likely never use. E.g., what are the odds you will need cone wrenches?

Don't take spares of items that will likely not fail or that you can live without even if they do. I remember a BF poster's gear list that contained, among other things, a backup flashlight.

Related...Like food, batteries and the like can usually be bought along the way when/if needed, so don't bring extras.

Clothes can vary signficantly in bulk and weight. Let's assume you need long pants for climate or cultural reasons. Leave the heavy, bulky Dockers or denim at home and instead carry light "conversion pants" that double as shorts. And take one pair, not multpile pairs. Also choose any off-bike footware with weight and bulk in mind.