DIY
If you can do things yourself do so. It's much easier to avoid processed food that way and gives you the option to control the salt and sugar content and unnecessary chemicals.
Grated cheese for example is coated in anti caking and cost more for less So why not grate your own.
Shop bought sauces are filled with sugars, salt and preservatives which wouldn't be necessary if you made it yourself.
Use your senses
All five senses are used when cooking, if you're an inexperienced cook it's important to pay attention. It is very easy to become distracted and turn away from a boiling pot and it over flows or take a phone call and lose track of how long you have been cooking a piece of steak.
As
@BaldingSoHard above pointed out tasting is cooking. Taste, Taste Taste. Taste when ever you add something, and if you need to add more then add the ingredient and taste again.
Balance and correction
You want to make sure your food isnt overly spicy. If your protein is spicy, your sauce is spicy and your rice is spicy then your food will not be enjoyable.
In cooking you will have to learn how to correct dishes if you over salt or over spice dishes.
For example if you are making a soup or sauce and it's too salty put a peice of raw potato into it. This will absorb the salt. When you feel the flavour is balanced fish out the potato and discard.
You can add a teaspoon or so of sugar if a dish is too tangy or salty. Tomato soup or tomato sauce for example.
For a soup or sauce you also add water to reduce the salt content but bare in mind this will water down the integrity of your dish and you will have to reduce or "cook down" the dish.
Reduction
Reducing is cooking the sauce, gravy,soup or stew to reduce the water content. This helps to concentrate the flavour and meld the spices and aromatics together. If you reduce it too far it can become too salty and you will have to add more water and cook it down again. You cannot just add water and turn it off, you have to cook till it combine all the flavours otherwise it will taste watery.
Multitasking
You want everything to be ready to eat at the same time. The dish that takes the longest must always be the first dish you start working on. The cooking time of the rest of your dishes will based around that.
Separately you dont want to wait till the main dish has finished cooking before you start cooking the second dish. E.g if your chicken takes 1 hour to cook. Start cooking your rice when you have 25 mins left at the same time start prepping your vegetables so you can put them on in the last 15mins. That way everything is ready to eat at the same time and is cooked within the shortest time possible.
Rice
Rice can be tricky if you over think it. The easiest method is the absorption method.
1. Always wash your rice. You want to wash off the excess starch which can cause your rice to be sticky. I put my rice in a strainer and run it under the tap swirling my hand through the rice until the water runs clear.
Then I put the rice in a saucepan and cover it with a finger digits worth of hot water from the kettle. When adding water remember that the water is also going in between each rice grain and the water on top that you can see is not all the water there is. Add a knob of butter and salt. With salt you have to add it to your own taste. Always taste the water after adding salt ensuring you haven't added too much. Remember you can always add salt but never remove it without starting over.
Turn the fire onto the lowest it can go. Remember the water is from the kettle so the cooking process will begin immediately.
I cover my saucepan with aluminium foil sealing the edges so no steam escapes. The rice will take 20 mins with this method. No stirring or anything. You will know when the rice is done because you will smell that "cooked rice smell" before opening the pot.
If you haven't added enough water you will hear the rice sizzling because the liquid has dried out, or you will also smell it burning. It shouldn't come to the point where it is burning in that short amount of time. So you will only need to add a small amount of water. Only enough to just cover what you imagine would be the base of the pot. Seal again and allow it to cook until you smell that cooked rice smell.