If you are interested in learning how to make chiptunes and only remember one thing, let it be that there is no more effective teacher than experience. Don't put it off by telling yourself you don't have what it takes! That's time you could be practicing, learning, building confidence, and getting better! Be kind to yourself and understand that the first songs will have flaws. Focus on what you can learn from them! I personally learn more from struggling with a challenging song than I do from one that comes easy. I try to frame my challenges as investments that provide reference to make future songs great.
As far as actionable tips, I have a few:
Expand your musical horizons! DUSTINODELLOFFICIAL uploads high quality rips (the actual kind) of hundreds of Genesis soundtracks, while GSTChannel's GSTMIX groups music of many different retro systems by style, application, and more.
2. Hone your ear, understanding of technical limitations (if you care to follow them), and ability to recognize harmony by listening to deconstructions of songs. Carpathia808 is a great resource for these videos.
3. Time to get technical? Check out some of the videos and playlists below for some insight into instrument design and basic music theory. I would say familiarity with scales, names of notes, time signatures, and simple chords (three-note Major and Minor) is enough to serve as a guide through 90% of situations without getting bogged down too early. Instrument design is a continual learning process that I would say never really ends and is best faced head-on through experimentation.
4. Join the community! Chiptune enthusiasts are generally eager to welcome new people into the fold. The Furnace tracker Discord is a great place to ask questions, get feedback on works in progress, and listen to others' songs for inspiration.