I just do what sounds exciting and have a backup plan. Sometimes the backup is simply to sit in a green space. The more you travel the more you can predict if some attraction is the same as it is everywhere.
Take the advice of very few people. “OMG you haaave to go to this restaurant”, is only worth listening to if this person goes to a lot of restaurants. When people say something is good, they really mean they had a good time when they went, maybe they were only having a good time because it’s their one week off a year.

>How do you do reconnaissance on a country before you visit?
skim over wikivoyage, atlas obscura and a tour site like getyourguide
watch a few youtube videos, preferably of expats or locals, avoid professional youtuber normie couple content slop
go on google maps street view and walk around the center of town
find the country or city specific subreddit and filter for english posts
search the 4plebs archives
change tinder to that location to do market research

>>2915744
>I can't help but feel I could have wasted less time if I had researched a little more.

>Everything I found was advice like: "visit Chatuchak weekend market." Which was garbage keychain/fridge magnet bullshit.

low information is better. all the research you can find is lowest common denominator garbage. get there and figure it out. the only thing you can do to prepare is to study the language as much as you can. even a complicated language like thai you can at least learn how to read in two weeks. if its a language i already know i spend two weeks immersing in it beforehand so when i arrive it's ready to be used.

>>2915744
I start with skimming through package tour itineraries. These are usually a hellish rush through a list of the country's top sights but they make it easy to get some general knowledge of what would be a shame to miss.
Then I look up a few janky old web 1.0 style travel blogs in my native language for any more obscure locations. English content is universally worthless since it's been completely taken over by either people copypasting flat out wrong bullshit from each other or just LLMs doing it for them. I supplement with a local cheapskate travel forum that's packed with people who've already been to dozens of countries and have no product to sell. There's cancerous forum drama of course but I trust them a lot more to be properly picky than a random TravelStacy.com dumping her favorite instagrammable cafes with endless positivity.
Finally, when I settle on a general area, I just click through Things To See on TripAdvisor, the most normalfag site of them all. There is a sweet spot right between the main sights and the glorified ads for illusion museum tourist trap shit that'll have cool and not particularly obvious places like giant trees, urbex spots, weird hidden shrines and the like.
Sounds like a lot but it's honestly just a few hours of work for a trip that'll last a month.

Also seconding >>2915890. The more experience you have with any hobby, the easier it gets for you to instinctively weed out the trash from everything on offer.

This is why I never go anywhere for less than 3 weeks. First week I just settle in and orientate myself and figure out what to do on my own.