Can someone explain to me how the Fortune Teller works?

[Chaos bacon]

I've never understood how to take advantage of the fortune teller. Like, what should I do if it says I have good luck, and does it even mean anything?

 

[Terdin]

It is an indication of your base luck that day. From +1 to -1. So, a day with the best base luck would be similar to if it was completely neutral (really rare) and you ate a dish that gave you +1 in luck, as far as I understand it.
A good luck day is good for going mining, or fishing if you are good at getting treasure chests. There's a bunch of other stuff that's affected too. Any time the outcome of something seems down to luck, luck is likely at work.
One effect is kind of counterintuitive. Having good luck during a storm leads to more lightning strikes.

 

[Nonak]

You can see everything it affects here, but the main things good luck does, (both daily and buffs from food etc.) is:
- Increases your chances to find a ladder/shaft. Useful when you're trying to get to the bottom of the mines or for a deep dive in the skull cavern for iridium.
- Increases your chances to find a treasure room in the cavern and geodes in any mine.
- Better chance to get a treasure chest while fishing, and the chance of that chest being golden, if you have the fishing mastery.
- Better items from panning
I think that's everything important

 

[Chaos bacon]

ok thx!

 

[ThatOneTposingDude]

Luck also affects artifact spots and gross drops.

 

[EliteDangerGamer]

good luck=good day
bad luck=bad day

 

[FilthyGorilla]

You can see everything it affects here, but the main things good luck does, (both daily and buffs from food etc.) is:
- Increases your chances to find a ladder/shaft. Useful when you're trying to get to the bottom of the mines or for a deep dive in the skull cavern for iridium.
- Increases your chances to find a treasure room in the cavern and geodes in any mine.
- Better chance to get a treasure chest while fishing, and the chance of that chest being golden, if you have the fishing mastery.
- Better items from panning
I think that's everything important

Pretty much, and the casino win rate and ore vein spawning (though those two are already to a smaller degree), it affects a lot more but the degree to which is really overblown, you'll get like 0.3% more wood on the best luck day vs the worst and it isn't really something to plan a day around (besides for mining, especially early game)