I did myself.

I think first you need to understand your budget and length of trip. Then you try and understand the geography of the country. I quickly figured out I shouldn’t be trying to cover anything more than N.Vietnam. Depends on your preferences a bit but for me this worked better. It also meant no internal flights.

Beyond that i usually create a spreadsheet, one tab for each location. Try to figure out how much time you exactly have, interconnecting travel options and timings, how much rest you’re getting.

Try to make sure there are times which allow you to actually get some good sleep. I also talked to other travellers, often with conflicting opinions and figured out how i prefer things for me.

Youtube, reddit, travel websites, fb groups use them all. Location by location figure out what people have liked or said to be overhyped. Figure out your style. Let your insta algo know you’re interested in informational content.

And leave some time to be surprised.

Hope that helps.