The best way to learn prepositions is to learn them in phrases. Too much analysis is a waste of your time and energy.
As well as "go on a tour", you also have...
go on an excursion (or outing..)
go on a journey (or trip, voyage, cruise...)
go on holiday (or vacation...)
go on a date
Perhaps you might see a pattern here?
Peachey is right. Just learn them as part of a phrase. It‘s just something you have to get used to. I know it’s tedious, but it can be done. My second language is German and it’s the same thing. You just have to know which prepositions go with which verbs, and which to use to form which expression. German often gives you a choice of two or more different propositions which can appropriately be used in a phrase with the same verb to say the same thing. Sometimes there are North vs. Southern German variations where you’ll hear one proposition used in a phrase in the North of Germany and a different one for the same phrase in the South of Germany. In a way, that’s kind of nice, because if you mix them up, neither is technically wrong, just more regional sounding.
Im a native US English speaker, so it’s just something you pick up as a kid. But, I’ll never forget something growing up. My little sister used to always say, maybe about age 7 or 8, „I did that ON accident.“ I guess at the schoolyard kids said that. I don’t know. This drove my mom nuts hearing „on“ in this sentence and she’d always correct my little sister, „It’s BY accident, not ON accident!“ I think after being corrected about 50 times, my younger sister started saying „by accident“ and never said „on accident“ again. Funny how I’ve never forgotten that.