+1 to everything on David's excellent list above.

Don't be daunted; you're on a fun learning curve, practice most definitely makes perfect in the art of songwriting and home recording!
But with all the tools at our disposal these days, particularly BIAB RealTracks, the challenge has become learning which tools and techniques NOT to use.

'We've all been there' example:
You find a nice RealTrack, maybe some guitar chord or single string noodling. You like hearing it, so in it goes, all the way through the song. Why not, it's cool. Ok, what's next.

Hang on. People listen to a song because the song makes them want to. So songs need to keep them interested. Two techniques present in almost all successful songs is "build tension/then release" and "leave spaces". A cool guitar noodle will cease to be cool after a couple of bars, and become downright irritating after a short while. So (eg) put it in the intro then drop it out. Make the listener hang in there hoping it'll reappear. Maybe bring it back in during a guitar solo in the middle. Drop it out again until the outro.

I put all my sound selections and arrangement decisions through this filter: "Is the listener going to find this interesting? Does the song build throughout, i.e. is something a little different happening every few seconds to hold the listener's interest until the end?" I'm particularly on my guard when I think I've found something 'cool' - will the listener also find it cool? If not, it's out.

Songs web site
YouTube Channel
BIAB 2019
Cakewalk by BandLab
Studio One 4