1. Use a good recipe.
You could be the world's best cook, but if you are using a faulty (or simply disgusting!) recipe, you won't like the results. I find that the best recipes are ones that have become family favorites. Few people possess the absolute best recipe for everything, but most people do have a few really great recipes that have become everyone's favorites.
Ask people for their favorites. When retrieving recipes online, look for recipes that have been reviewed by other people and are highly rated. If you eat something that someone else made and you really love it, ask them if you can have their recipe! Most people are delighted to be asked for their recipe! I know I personally consider it to be a high compliment. ;)
2. Use good ingredients.
Always try to use the freshest and highest-quality ingredients possible. (And preferably, the exact ingredients that your recipe calls for!) Sometimes good-quality ingredients are more expensive. Often, if you know what you're looking for, you can purchase something that's better for less money. How?
Well, for example, freshly ground black pepper is much more flavorful than the pre-ground black pepper, and peppercorns are usually the same price as ground pepper (per pound), so all you need is a pepper grinder, and you can have high-quality freshly ground black pepper at the same price.
3. Allow plenty of time.
The "preparation time" listed for recipes tends to be the time required under ideal circumstances (e.g. you have made the recipe before, you know where all the ingredients are and can locate and measure them quickly, etc.). Whenever you are making a new recipe for the first time, start early so you can take the time to follow your recipe accurately and not miss anything. Even if you are a quick and experienced cook, it never hurts to allow extra time.
You also don't want to be rushing through the preparation of your foods, having to turn up the heat to boil things quickly or cook them faster. Some things can be hurried, yes, but many meals are ruined from haste. "Quick cooking" should be the result of either a simple recipe or experience in the kitchen, and not result in burned foods. ;)
4. Think ahead.
If you're making a new recipe, be sure to read through the recipe to see if you have all the ingredients. Your recipe might also call for something at room temperature that you need to thaw or set out ahead of time. If you have a microwave, you might be able to soften cream cheese at the last minute, but it saves time and hassle (and produces better results overall!) if you just think ahead and just set it on the counter to soften.
5. Use enough salt or other seasonings.
If your mexican foods are tasting bland, try adding some hot sauce; even if you don't like extremely hot foods, a little hot sauce (we like Tapatio!) will add some flavor. If your gravy needs some more flavor, try adding black pepper or some (MGS-free, hopefully!) bouillon. For heavy tomato-based foods like chili or tomato soup, we like a little white or brown sugar added.
However, the main "seasoning" that is sometimes overlooked (or simply forgotten!) is salt. Having the perfect amount of salt is essential to producing great-tasting meals. It's best if you are able to actually sample your food as you are cooking to determine what the perfect amount of salt is. If you have had a lot of experience in the kitchen, you might know how to estimate how much salt various things need. For example, we tend to like extra salt in things like gravies or white sauces and potato soups. Still, it's good to taste your food to be sure it's seasoned correctly.
If you taste your soup or gravy and it seems to be missing something, try adding a little salt and tasting again. Often an "only okay" meal can be transformed into a "great" meal with a little table salt!
6. Follow recipes exactly.
Yes, I know, I don't do this. But my food doesn't always turn out great. My lasagna gets watery, or my bread dough is too sticky (since I use the bread machine to knead it ;D). My food might still taste good, but when I take the time to follow a recipe accurately, the results are even better.
If you're like me, and you hate measuring everything and following every little instruction, then you may just have to go through some trial and error to discover what's okay to "fudge" and what's not. ;) When you've done a lot of cooking, eventually you learn that melted butter won't always work when a recipe says "softened butter", and that it's not always okay to just mix the ingredients in whatever order you feel like mixing them. And if it doesn't say to use an electric mixer, yet you beat it on HI for 5 minutes (because you hate stirring ;D), depending on what you're making, it just might not turn out like it should. ;)
7. And lastly, good technique.
I put this one last, because it really isn't essential to cooking. We all started out as beginners at some time, and learning good technique is a result of years of practice.
Being experienced at, say, rolling out pie crust, will produce better pies. But don't ever be discouraged by your inexperience. If you need some cooking help, find someone who has had experience at making bread, canning, making pies, or whatever you wish to learn, and spend an afternoon learning from them. There are some great online videos and tutorials, if you have the time to study them, but I think the easiest way to learn cooking techniques is from hands-on, in-person help. If you're learning by yourself, start small (bake homemade muffins rather than homemade pies!) and gradually learn to make new things!