I've been an amateur Photoshop user for ages and have done layouts for several formats successfully. I know legit designers who tell me some of what I'm using PS for would be easier in Adobe Illustrator but I don't have the motivation to take up another software platform.

That thing can do a million things and I use about 10% of them, but once you get the hang of layers and basic editing tools you can get a lot done.

My process* has more or less been to start with my or the band's own ideas (whether photo, hand made art or drawing etc.), have a direction or aesthetic you're aiming for, then to have a graphic designer pull off the more technical aspects. That way you end up with something that looks personal and representative, but also not like someone's first attempt at Photoshop/Illustrator etc.

I'm sure there are album art-focused graphic designers on fiverr but I haven't gone down that road personally.

*edit: I just mean for stuff that went to a printer. For digital releases with a little thumbnail album cover you can get away with almost anything.

Affinity Designer.