Yo!

Arrangement is huge. I try my best to first get a main idea down, usually something along the lines of some chords and some sort of hook / drums. Once I have the main idea I really try to just capture the vibe and "feel it out" as cliche as that may sound. Try and figure out what you're going for and really, just start shooting at it until something sticks. It can always be a huge help to reference songs and I recommend really digging into the music you like, and don't like, and looking at the arrangement. Study what elements help drive the song. Once you get something you're happy with, render it out, open up a blank project and just slice it up and play with the sections. This will help give you a broader view of the arrangement as you're not dealing with individual channels but instead the song as a whole. In the end, if things aren't working out, give it a break, take a walk, change the key, work on a different project. Just push yourself and have faith in the process