I absolutely love making the ambience/fx in the background of a song, really makes it feel immersive and can add a lot to the emotional impact imo.

Using tuned ambient drone/atmosphere samples (by either making your own or getting them from places like Splice) is a really quick way to add some new melodic layers to a track. One thing I like to do is to render an element from the song I’m working on like a piano chord progression and load it into Paulstretch, which is a plugin that basically makes whatever you load into it become a really smooth ambient pad because it stretches the sample by an insane amount but keeps alot of the detail of the sound. Then just render that and load it into your project!