> Form good habits for a clean Mac
Don’t dump on desktop
It’s tempting to drop everything on to the desktop. Don’t! Use it to house a single current project, or as just a temporary location for files.
Downloads Zero
You’ve probably heard of Inbox Zero — dealing with every email by the end of each day. Do the same with downloads. File anything you want to keep, then get rid of everything else.
Minimise new app installs
There’s no point cluttering up your Mac with apps you never use. Figure out those that help you most and/or you enjoy, and scrap the rest.
Avoid duplication
Many files have their proper place — they don’t need two. For example, say you download music from Bandcamp and drop it into iTunes; assuming you allow iTunes to organise your media, you no longer need the originals in Downloads.
Sensibly name items
Cruft sometimes appears over time because you don’t know what — or where — your documents are. Figure out useful naming and filing conventions and then stick to them. You’ll be more likely to find and use things that you’ve previously saved.
Consider gamification
If it’s tricky to get good habits going, gamify them. Momentum Habit Tracker (Free, Mac App Store) gives you three free “habits” you can track, one of which can be a daily attempt to keep your Mac cruft-free.