This Wikipedia page is very useful in helping us figure out what kind of visa preparations we should look into for any given country. It makes it super-easy to look up whether it’s necessary to apply for a visa before getting to the destination, if we can just relax and obtain a visa on arrival, or if we don’t need any visa at all (or even a passport, as is the case for countries in the Schengen Area).
Adding to that, and given our slow travelling pace, it’s always very important to be aware of the different timings involved. For instance, a regular visa on arrival will grant us only one month in Indonesia or the Philippines, while it will mean a maximum time of 90 days in both Taiwan and Malaysia (bless them).
This website can also be quite useful in keeping up with the visa situation in more unpredictable countries like Thailand, which has recently been closing in more and more on foreigners living there for long expanses of time without any working visa or permanent residency status.