Maybe a bit of research on local customs and a few words in the local language for please, thank you, and ... for the different countries to be visited.

Check currency exchange rates and costs and incorporate into trip budget (eg, while not applicable in this case, the Euro and sterling and even the US dollar are worth lots more than the Aussie dollar because of the latter's slide in value in the past 12 months. It's become a moving target...

Purchase necessary pharmaceuticals, medicines, after checking legality of taking them into other countries.

Establish potential "escape" plans if things don't work out too well.

Will?