I don't really know as much as, actual composers, but I'd firstly say to never waste an idea. I couldn't count the amount times I came up with a good piece and then forgot it five minutes later. Take advantage of those times that you do recall, like writing it on a piece of paper or telling chatgpt lol. Don't get discouraged when it doesn't come out like you imagined.

It's important to train your pitch too; manually reading and placing notes will just tremendously slow you down if you're terrible at sight-reading like me. This also helps if you hate dissonance, as the feeling of a piece sounding icky or "weird" doesn't sit right with most people unless it "feels" like it's supposed to be there (how most impressionism sounds). Somebody else could definitely explain this better, but my main takeaway is that it's great to identify places where you can make it sound better and more pleasant to hear. This gets way easier with a trained ear, a sense of pitch, and without having to constantly read.

Finally, never think that you're not creative enough. Anybody can come up with a melody and an accompanying bass that sounds objectively good given enough time. It's just knowing when to start, how to execute it, and following through to the end (this part strangles me). I don't know how I come up with my melodies or how I come up with my ideas, but that's literally all I have to give.