Ten things those who cook for a living know that you should.

I'm not going to go all Kitchen Confidential and explain all of the things you shouldn't order at a restaurant. Anyone who thinks at all about what they eat should get that book and read it for themselves. These are simple, inexpensive things that make your food better:

1) Make use of Maillard Reaction. The short version is when you apply dry heat to food, it turns roasty toasty brown and tasty. It is what makes toast better than bread, and Grilled chicken better than boiled. Meat needs a little salt to pull water soluble proteins to the surface, and draw surface moisture away to get a dense brown crust, and as Anne Burrell is wont to say "brown food tastes good."

2) Speaking of salt, be liberal with it in preparation (don't make it unpalatable, but use its mojo). If you are eating unprocessed whole food 99% of the time, it is very difficult to season your food to the point where it is unhealthy.
Salt does wonderful things to food (see above) and literally changes the structure of food. If you want vegetables to break down, salt them early in the cooking and the salt will help to pull the moisture out and will aid in browning. If you want them to maintain their structure salt them later in the proceedings.
An important point is the stuff in the blue canister "when it rains it pours" stuff is junk. The grain is too fine, and it tastes acrid and chemically. It's over processed the enriched white flour of salt. Get the equivalent of whole grain: either kosher, or sea salt. Try several and find one whose texture you like. This brings us to...

3) Quality counts. Executive chefs spend most of their time sourcing food, and finding pantry ingredients that work for their food. This is the true difference between a great shop and a mediocre one. Good restaurateurs know their purveyors they bully, or bribe them if need be, but they get the best food available. You don't need to go to this extreme; you only need 5 apples, not 500. Going to a couple stores and being friendly goes a long way to getting the good stuff. Buy stuff that is local. Buy it as close to the source as you can get, and for all that is holy buy stuff in season.

4) Store it right. Once you've gone to the trouble to get the good stuff, store it right. The best way to tell is if it was on ice in the store put it on ice at home. If it wasn't please don't. There is nothing worse than a tomato that has been put in the icebox.
Most proteins must be chilled for safety reasons, but appreciate being allowed to come to room temp before facing the heat. Particularly eggs, and red meat (be careful with store bought ground meat, and unpasteurized eggs) the exception here is raw tuna. I keep it mostly frozen and let it face the heat. That way the center stays rare even though the outside is crusty and brown.

5) Thaw it right. I love using frozen items, but you have to give it time to come out of cryostasis. Put it in the fridge 36 hours beforehand, or if you need to quickly thaw it, plunk the whole package under COLD barely running water. It may take longer, but any other method either damages the food, or puts it at risk for rot.

6) Use spices, and remember quality counts here too. Most folks, if they spice food with anything other than salt and pepper, go to their grocery and buy a little container of powder from the grocery. I understand not wanting to make a whole separate trip to buy whole spices. I get it, but there is no excuse for not grinding your own pepper, chili powder, cinnamon, and nutmeg. I keep a mill for pepper, a coffee grinder for Chile powder (if yours has a metal bowl wipe it out, and grind some cornstarch in it, throw out the cornstarch, wipe again to clear it's "palate") and I simply grate cinnamon and nutmeg with a micro plane grater. My personal preference for Chile powder is 1 ancho to 1 New Mexico (seeds and stems removed).

7) Don't boil anything. The only exceptions are starches, which you shouldn't be eating anyway. Broil, braise, sauté, but don't boil it.

8) Portion food correctly. It is better to cook more pieces of food in the right size batches than try to make one supersized batch. It may take more time, but the more raw food you put in a pan the longer it takes for that pan to come back up to heat. The bigger a piece of something, the longer it takes for heat to reach the middle. Which can lead to a raw middle surrounded by a dry overcooked mess. Be patient, cook in smallish batches.

9) Use the right vessel for the right job. Glass or ceramic for slow cooking (holds heat longer). Non-stick for medium heat, sticky foods. Metal for high heat. High heat can cause non-stick coating to leech into food. Most foods cooked at high heat will "let go" of the pan if given time, and not fussed with.

10) Don't be a slave to a recipe. Get the best stuff that you can, and adapt. Some of the best foods were invented because of substitution. Just make sure you think about the whole picture (texture, flavor, and cooking times) you may have to make adjustments to seasoning, cooking time, or temperature depending on the substitution.
This is the reason that dining at big chains is a problem. They have to keep the same foods on the menu all year round in every location. So they can't pay attention to quality, season, and location. Their food suffers in the name of convenience, consistency and preservation. To me that's not a fair trade.
enjoy your food.
If you have any of your own tips, let me know.
Mahalo.