There are some principles and techniques but the best way is to practice more and more. You will get to know everything that make a fx looks good and when you will know that by yourself that will tech you a lot of other things. Best of luck
design for a result is art fundamentals: form vs function --begin with reference/copying and then you advance them with your sense for abstraction.
principals of motion, color theory, composition, harmony, contrast, focus, and timing/rhythm
again, fundamentals you can pick up on within a few hours with online videos.
References are not just real-world; it can/will be other artist work you may try to relate with or emulate. Utilization becomes 2nd nature which is why techniques and methods are the areas for teaching/sharing.
practicing can be to take a screenshot of a game you like and make a fire or explosion for it that harmonizes or contrasts with it
I think what really helps me when doing personal work: do an effect with a ‘purpose’ in mind. This could either be for a specific design/ability I’ve done myself, or a vfx challenge, or a concept from the internet, or from a video ref.
Anything that inspires really, but also sets a specific frame of mind and a clear goal.