A piping hot pan and a cool piece of meat = a perfectly seared crust every time.
Freshly cracked black pepper and a variety of salts, from kosher to sea, make your food better with virtually no extra effort, as opposed to pre-ground pepper and table salt. (I keep kosher, pink Himalayan, and large-flake Maldon sea salt near the stove. And the very handy Pepperball one-handed pepper mill is always within reach.)
Homemade stocks are always worth it. Like exercising, nobody ever regrets the time and effort it took to do it afterward!
Mise en place is the key to sanity in the kitchen for complex dishes.
Music makes food turn out better. ;D
Nothing will EVER beat a quality set of knives.
Freeze your flour to keep it from going rancid, or allowing grain weevils to get in.
Ramekins are for so much more than creme brulee. Buy a few inexpensive ones and use them to hold ingredients, or even just a little salt and pepper, and be amazed.
Always fluff flour before measuring, use room temperature butter and eggs for baking, and use a little coffee in chocolate recipes to intensify the delicious flavor.
When making whipped cream, put the beaters and the bowl you'll be using in the freezer, and take them out right when you get the cream out of the fridge. It makes better whipped cream for me every time.
LET MEAT REST BEFORE CUTTING! I didn't know this when I cooked my first steak, and I learned the hard way!
Let pancake batter sit for a few minutes before actually cooking it; my pancakes are picture-perfect when I give my batter about 5 - 10 minutes to just hang out.
Keep practicing, keep watching other people cook, and keep experimenting! You never know when you'll stumble upon something ingenious, or just delicious.