First, LBD didn't have a very detailed premonition. She came out on top of the mecha laughing evilly, a possessed MK appeared in despair (I don't know if he was possessed, but he has blue eyes, so I'm going to assume that he was partially possessed), and then destroys the world.
Unless there are more details that we haven't been told, we assume that she had this premonition to guide her and follow her "destiny".
In "This Imperfect World" it is revealed that she had that premonition from the beginning and that at first she didn't know what it meant...
This makes me think that she was "improvising" in what her vision didn't inform her...
Her vision told her that her plan would work in the distant future, and that didn't discourage her from trying it in her present. She suspected that she would fail but she wouldn't die, so she made a plan B to free herself in case she was sealed, and that plan is Macaque. She saves Macaque from the underworld in exchange that, in case she gets sealed, he frees her from her in the future, which he totally ignores.
The case shows that she didn't know that it would be DBK who would free her, or that Macaque would betray her, which makes her think that she had a plan but she was also "improvising" along the way, and she was so convinced with the concept of "fate" (basically, your actions don't matter, there is only one journey and one end) that it didn't occur to her that there might be several "destinies" (that actions and choices do matter, and there are various possibilities, developments, and outcomes).
My theory is that she failed by not completing a series of certain actions or avoiding certain moments that would cause her doom:
1) She should have completely possessed Macaque. Since he, unlike Wukong (recognized to be the most ridiculously strong of all), is easier to control, she can add a "power up" to him, and use him to keep Wukong entertained, as Macaque can keep a fight with Wukong equally (besides the emotional weight due to their shared past). Not to mention that it would have prevented Mei from getting the Samadhi fire.
2) She should have possessed MK when she stole his staff, since her vision specifically includes possessed MK. Not to say he is the only one apart from Wukong capable of controlling the staff, but he is definitely easier to possess and control than Wukong, not to mention that MK together with the staff is a power up in itself. Not to say that Wukong and MK's gang would be unable to physically harm him and risk his life.
3) She shouldn't have tried to possess the Samadhi fire. Since in her vision the Samadhi fire doesn't appear anywhere. Neither pink fire nor green fire, only blue fire, which is her power. Besides that it entertained her enough which gave MK's gang time to fight back; the moment Mei controlled the fire, she would lose.
4) She shouldn't have possessed Wukong. Yes, he is the strongest and definitely a useful "champion", but at what cost? Macaque himself said it: the moment that she possessed him, that greatly limited her movements and powers. It was temporary, since Wukong would definitely free himself from her control, it was only a matter of time, and keeping him distracted (thanks, Macaque).
5) She shouldn't have messed around during season 3: Since the time that she spent preparing was the main reason the other characters got their powers (specifically Tang and Mei), not to mention that it allowed MK's gang to add allies like Red Son, Nezha, and Macaque (I will also count Chang'e, Dragon of the East, and Scorpion Queen, because it was their energy beams that helped in the end).
That's all. Thanks for reading.