Be Ready.

Having things ready in place.

Have you ever been halfway done with a dish and realize you didn't have the cheese grated? Now everything is on hold (and over cooking) while you grate cheese?

Having everything ready to go at the start lets you add the things when they need adding and helps put dishes out at the appropriate time. Johndough99999

Hold the Garlic. 

Never add garlic and onions at the same time.

Onions take about 8 minutes to sautee and garlic takes about 30 seconds. If you add them together you're gonna have burnt, bitter garlic. TaloonTheMerchant

I noticed that, but I actually really like the taste of burnt garlic. Not sure if it's gonna kill me some day :/ jasonml

Something Extra.

Thinking you need more salt when the dish just needs an acid like vinegar or citrus. Jioni92

I made a chicken fricassee dish for the first time last weekend and while the first few bites were delicious I felt like it needed a little something extra. I remembered reading this same tip in a previous Reddit thread so I squeezed some lemon juice on it and it was perfect! ummmnoway

Never Rest. 

Never letting meat rest... not keeping sharp knives, and just knife work in general... cooking should be simple and easy... fighting with prep work is never fun. Wheres_the_sand

Keep your fingertips tucked behind your knuckles and your thumb behind your fingers.

That way, the worst possible thing you can do to yourself is slice off a bit of flesh around your knuckle instead of lopping a finger off. moal09

Don't Tong!

Using tongs, you must clink them together at least five times to channel your inner crab. large00f

I worked in an upper class restaurant as a bartender and could see the kitchen and cooks stations from a little window in my bar. I like watching the cooks cook and it was a slow day so I was looking through the window when our head chef who trained in France under 2/3 of the guys that trained Gordon Ramsay scuttled past making zoidbergs woop sounds while clacking tongs in each hand. envirex

Watch the Soap.

Never put knives under soapy water EVER. I once saw someone put one in and they sliced their hand pretty deep, don't know how. Diamonds4days1

Almost cut myself like this my first day as a dishwasher at a french bakery.

Noped out of that job pretty quick though. I realized I don't want to work that hard for that amount of money.Diamonds4days1

Onions.

How about simply chopping onions. It's literally one of the easiest things to do if you use the natural anatomical structure of the onion in your favor. Most people hack it into oblivion, which not only takes much, much longer, but also results in unnecessarily sad-looking onions. Plus it makes you cry. ChanceGuest

Practice Makes Perfect. 

Practice your recipes. Don't find one risotto you like and never make a different one. Cook 10 different risottos two or three times each over a long period of time. Doing this helps you understand the basics of how to make it and allows you to spot bad recipes, recognize good ones, and improvise without one. Rezzone

Chopable!

Even on the food network I see chefs cut the top off of bell peppers and then pull out the seeds. Bell peppers are shaped like a cube, just slice from the top down on all 4 sides and you will end up with easily chopable or sliceable pieces. The only time you chop the top off is if you need rings. FakeRicky

Be Clean.

Not a chef, but pro-tip: clean as you go.

No matter how busy you are, throw trash in the trash, wipe up what you spill, get unnecessary utensils, plates, etc. out of the way.

If you're done cooking and your kitchen looks like a tornado struck, you messed up. Instead the kitchen should be 3/4 clean (at least) by the time the cooking is finished. Reddit

Assembly Line Method. 

I briefly worked in a tapas kitchen with a sous-chef who knew all of the tricks. He showed me his "assembly line" method, of always having a container/plate/bowl for your prepped ingredients and then a container/bowl for your scraps of trash and garbage (apple cores, garlic skins, etc). I am not a cook anymore, but still use this method to this day. It's amazing how much better it feels to cook in a clean space. shuispasunrobot

No Microwaving!

Ex-chef here, and this is a dumb one but I've seen it so many times in student halls. Don't microwave a damn steak, or eggs, to cook it. small_but_lazy

Perfect Pot. 

If you want perfect roasted potatoes (oven roasted, chopped pieces) with crispy outside and fluffy insides then boil them for about 5-10 minutes in salt water first. Then roast them. DeliciousMalediction

I would add a couple refinements to this comment:

Parboil until they're tolerable to eat as boiled spuds. While you're doing this, pre-heat a tray with fat. Oil is OK, goosefat is best

Drain and then shake (I recommend a collander). This roughs up the outside of the spud cubes for more surface area to get crispy.

Then put them in your tray and mix so they're nice and fatty.

For bonus points, throw on some breadcrumbs and herbs. DuckWhispers

Don't Ruin the Edge. 

Putting you knives in a drawer. It ruins the edge. A dull knife is a dangerous knife. (Because you can't slice through the food and you struggle, this results in an injury.) MorbeMaddness

plate warmer setting

Just finished that awesome, wholesome, home cooked and hot delicious meal? Don't put it on a cold plate from the cabinet. Some ovens have a warm plate setting or even keeping a stack in hot water and drying them off right before plating can keep a hot meal hot. I always hated cooking an awesome dinner and then by the time I've served everyone and sat down my food is cold because its sitting on an ice cold plate. Hell even some of the newer dishwashers have a plate warmer setting. MaybeItsJustMike

Yes Brussel Sprouts!!!

Most people suck at roasting vegetables. Brussel sprouts are the number one mess up and most people lose their mind when I serve them properly done brussels.

Toss with olive oil (more than you think), salt (more than you think), and any other herbs/spices (e.g. curry spices with cauliflower), lay cut side down on a baking sheet, and throw that into a 200C/400F oven until it's visibly browned. Depending on the veggie (e..g carrots) you'll probably want to turn over to the other side and continue roasting for a bit. Once they're done you can toss with pepper or fresh/delicate herbs before serving (e.g. mushrooms with tarragon or parsley).

Just because it's fork tender and cooked through doesn't mean it's delicious. Yet. biologicalsequins

Be Sanitized. 

Not sanitizing your hands and work area after handling raw meat, especially chicken.

Can't count the number of times I've been cooking with friends or family and have to stop them from chopping salad veggies on the same cutting board as raw meat, or running their hands under cold water for a second to 'clean them' before going to grab stuff out of the fridge or drawer or even just going about their day.

Same goes for giving your slimy raw-chicken cutting board a quick scrub to wash it using the same sponge you use for everything else.

If it's touched raw meat, it needs to be throughly cleaned and sanitized with hot water and either soap (your hands) or bleach (everything else). Pitchesotoole02

Sharp Knives.

Sharp knives. Makes things a million times easier, and is actually soooo much safer in the end. Combined with the proper grip and a bit of practice, and suddenly cutting things for prep goes from the most hated step of everything to just another step, maybe even becomes fun for some people. ALELiens

Use a Temp!!

Not using a thermometer when cooking meat.

By using a thermometer, even a novice cook can be sure that they are cooking their meat to the desired level of doneness. You may not need to use a thermometer after you've cooked a certain cut of meat a few times, but for new recipes and types of meat, a meat thermometer gives you confidence and precision. BullGooseLooney904

It's the fat! 

It is the fat that carries the flavor. If your going to sautee something, put the herb and spices with the butter or oil that is in the skillet. Don't put them in the flour you're using to bread the food. FatuousOocephalus