Learning how to effectively prompt an LLM is an enormous space in its own right - and there's no shortcut for it, you have to actively play with the things.
I've been using them constantly for over a year at this point and I'm still figuring out new tricks and strategies all the time.
Weirdly, knowledge of Machine Learning isn't actually that relevant to getting good at using LLMs to solve problems and build software.
Knowing how to train your own neural network will do little for your ability to build astonishingly cool software on top of existing LLMs.
Knowledge of how LLMs work is useful, because it can help you prompt them more effectively if you understand their limitations, have an idea of their training data etc.
I've seen people (who I respect) argue that deep knowledge of ML can be a disadvantage when exploring LLMs, because it can limit the way you think about and interact with them. Weird but possibly true!