…Treat every success in your fiction like it’s a clue. In other words, hide the holy shit out of it. Hide it in plain sight. Break away the second before the character succeeds, and show them after a time jump, struggling on the next thing. Show the bad guys flipping every success on its head. Lie. Bury the success in a list. Have the other characters mock the success.
In the end, the character has to have done a lot of things right. But don’t let the reader know that. “That guy,” they should be saying, “he just can’t get a break.”