What are the best cooking hacks you've learned over the years?

Clean as you go, don't just leave it all for the end. Onions are sauteing and you're done chopping everything? Good, wash your cutting board and knife and clean up any messes before the next step. Sausage is done browning and you're dumping it in with the onions for a minute with the garlic and some herbs? Great, wash that pan and spoon and set it down to dry and wipe up all the oil splashes.

Just makes clean up so much easier after you've eaten and you're much more efficiently using your time.