1. Every time you get an email you don't want, instead of deleting it, hit unsubscribe.

Obviously you can't do this if the painful email is from, say, your boss, but taking 10 seconds to remove yourself from an annoying email list will make your inbox a shitload easier to manage.
2. Clean out your wardrobe with this clever coat hanger trick.

At the start of the month turn all your coat hangers to face one way. Whenever you wear something and return it to the wardrobe, turn the hanger the opposite way. At the end of the month you'll be able to see what you didn't wear once and can consider getting rid of it.
3. Once that's over, reward yourself by replacing your wire coat hangers with plastic or wooden ones

Thick hangers won't stretch or ruin your clothes like wire ones can. You can get six for $5AUD from Kmart.
4. Check the expiry date on everything in your fridge and cupboard.

It's also a good idea to try to remember when you froze things too, as different types of meat have different expiry times, even when frozen.
5. Go through your plastic container stash and get rid of anything that doesn't have a lid.

It'll be worth it when you're not drowning in a sea of plastic every time you open your cupboard doors.
6. Also check the expiry dates on all your beauty products.

Most skincare and makeup items will have the symbol above somewhere on their packaging. This indicates the length of time after purchase date that the product is useable.
7. Clean out your wallet, purse, or handbag.

Honestly, you don't need all those receipts. Nobody's going to be asking for them.
8. Pack away your heavy winter wardrobe once the weather warms up.

Even if you have enough room in your wardrobe it will make the space feel fresher.
9. Fix the things you've been meaning to mend forever.

Before you buy yourself new stuff, get those jeans taken up and sew that missing button back on.
10. Start ~thinking~ about any gifts you need to buy over the holiday period, even if you're not actually going to start shopping for months.

Basically, when you see something and think "Blah Blah would love that", just write it down so you don't bloody forget.
11. Back up your phone and your computer to a hard drive.

The sooner you make a habit of this, the better your life is going to be if anything bad ever happens to your shit.
12. And set up automated payments where you can.

If you're in the right ~cash situation~ setting up automatic payments for reoccurring expenses like rent and bills can save you a ton of hassle each month and make your budget easier to manage.