There are a lot of things that you need to remember when cooking. I am going to list them here and add to this list as I remember.
Always notice how big and puffy your meat is when you first start to cook it. As it cooks it will shrink. It is one indication of how done the meat is. This is the case with most meat.
Always notice the color of the blood coming out of a steak while its cooking. Bright pink is rare. Red is medium rare. Reddish brown is medium. Brown or none is dead, dead, and dead.
In the case of some meats you should always notice how the meat feels when you depress it with a fork. As you cook chicken, the meat will get softer and easier to penetrate. However, if you cook it too long then it begins to get harder again. Beef is different, depending on the meat you are cooking. A steak, in general, will get harder as it gets closer to well done. However, a pot roast, like a steak, will get harder as it gets closer to well done. However, a pot roast gets more tender as you cook it past well done. Of course if you cook it too long then it will get harder all over again. In general, most meats and fish will get harder the longer they cook. Once you know about the meat you are cooking you can use that as a guide as to how done it is.
Always know what is in the ingredients you use to cook with. For example: If you are cooking chicken soup, you may want to add chicken broth to give it more flavor. Most chicken broths have a tremendous amount of salt in them. So, the last thing you want to do in that case is add a lot of salt to the soup when you know you are also going to be adding chicken broth. Another example is Greek Seasoning and/or Italian Seasoning. If you add a lot of Greek Seasoning and/or Italian Seasoning to anything, don’t add a lot of pepper. Trust me, you don’t need it.