Big lottery tickets are, as noted, associated with some publicity - though a few states do allow it to be done anonymously. Arranging for a single Powerball win in such a state seems to me like the best bet for a quick one-off win that does not require ongoing work: you’ll have to pay taxes etc, but once that’s done, live a quiet-ish lifestyle and you’ll likely go unnoticed.
What powers would you need to do that? Being able to see the future is pretty obvious - but you’d need to be able to pick a number that only one or two players had picked. Then you rush to that state, and buy your ticket with that number.
Alternately of course you could have telekinetic powers that would force the little ping-pong balls to select “your” number. No way of knowing how many others had that number, though.
Stock market is a bit trickier, especially if you want a one-and-done windfall. Someone suddenly making 100 million in the stock market might get the attention of someone at the SEC. You’d need to do it much more gradually - start with a few thousand and very slowly ramp that up into the millions. Even so someone might notice it and start investigating you for insider trading. Hard to prove that, of course, but you don’t even want the hassle, right?
But as with the lottery, a certain amount of precognition would be called for. OR the ability to influence luck, or randomness, or something, so that it turns out your way more often than a simple coin flip would suggest.
Finding rare minerals etc. is a good one, if a lot more work. You want it to be on the up-and-up, so you’d have to be able to locate gold or whatever someplace non-obvious that isn’t too expensive to get at, and purchase that land cheaply. If your power has the ability to, say, raise a vein of gold that’s 150 feet underground, to 30 feet underground, that would certainly help. Clairvoyance and/or telekinesis are your friends here.
Predictive abilities - a bit more subtle than “what are tomorrow’s Lottery numbers” - would be a good long-term plan. If you know what things will be trendy in a year, you can invest in those. If you know what wars are likely, invest your money accordingly. Some kind of psychic ability to influence such trends could be useful as well (See Connie Willis’ book Bellwether).
Teleportation is a pretty good go-to skill, if your aim is to get rich and you don’t care about stealing. Steven Gould’s book Jumper is about just such a person.The downside of a cash theft is laundering that money. You can buy a lot of stuff with cash, but nothing like a house or car. If you steal art or other valuables, you need to have a trustworthy fence and a way of getting paid into a secure bank somewhere.
The ability to affect others’ emotions would be pretty useful. Imagine you wanted to get into acting. If your ability wasn’t just for people in the room, but everyone who saw you even in a movie, you could be dragging in massive movie salaries for a couple months a year of work - none of that working your way up the ladder and proving your chops stuff, but literally an instant hit… Get a good agent, get good deals on residuals / royalties / whatever, make movies for 5-10 years, and never work again unless you want to.