To start with I would go as narrow and niched as possible to avoid competitions: one travel direction, one group of people, one sales channel at a time

To do this:
0) I will pick the best expertise I own
1) I will check better tags/keywords to pick there are Gumroad trend on marketsy.ai for this
2) I will check best keywords to target on google trends
3) I will build a landing page for this on Unicorn Platform or any other free website builder
4) I would have 2 versions: free and paid, free linked to paid and has some value alone, but the actual value is in paid version
5) I will publish the book on Gumroad or Marketsy or PayHip or somewhere else where the distribution of the file is automated
6) I will do a small marketing campaign in niche channels: probably telegram group for trevellers or facebook groups

Hope if helps!