The number 1 thing I could suggest to improve one's cooking is to learn to add the proper amount of salt. Most of the time food is bland because it isn't salted enough. Salt has a flavor, but it actually intensifies other flavors. The key is to add enough salt to bring out other flavors but just short of becoming "salty"
It's not easy coming up with a standardized amount for salt because people have different preferences and sensitivities as well as many other factors; however, there are some guidelines you can use.
2% salt is often considered the threshold of what the tongue considers palatable. I use this as my upper limit, but what's the sweet spot? If you look at many salty, savory snacks like chips you see about 1% salt. That's where I began and I found that I like about 1% (5g salt/lb). That means about 1 teaspoon of salt per pound of meat. I use this only as a guideline and always add 1/2 of it first and slowly add the rest and stop when just right (I trust my senses more than formulas).
Application: Usually I take about 3/4 teaspoon salt per pound and rub it into the surface of steaks and roasts about 2-3 hours before cooking. Use it when making mashed potatoes, grilled veggies, marinara...whatever dish where "add salt to taste" is written, use this as a guideline
There are many other factors, usually dish specific, so sometimes you need more or less than 1 teaspoon salt/lb to get 1% salt.