How long and where will you be going? Besides the bare essentials like clothes and toiletries, bring along his favourite snacks, a favourite toy or book to keep him occupied when needed. Also decide if you wanna bring a stroller (preferably one that is foldable) cos toddlers get tired easily and you might not wanna carry him around all day.
Thanks for the advise! We're going away for about 4 days to HKG. Definitely bringing a stroller, can't carry him anymore