What makes the difference between a good cook & a great one? In my opinion, it’s layering of flavors. You can make a decent beef stew by putting raw beef, water, vegetables & spices into a crock pot & letting it cook all day. The meat will be tender, there will be some flavor. But how do you make a great stew? You take the same ingredients & add a few steps.

First step-browning the meat. By carmelizing the natural sugars, you’re adding wonderful flavor as well as texture & color (remember, we eat with our eyes first!).
Second step-use broth instead of water. Homemade is best, but, let’s face it-who has 12-24 hours to spend lovingly tending a pot of beef stock? If you do, awesome! If you don’t, there are great premade broths available at your nearest grocery store. I prefer ones that are MSG free & reduced sodium-it gives me the opportunity to season to my taste.
Third step-sauteing or roasting vegetables before adding to the stew. Again, the process of carmelizing the sugar adds color & flavor.
Fourth step-adding seasonings, herbs, additional flavors.
Fifth step-taste as you go! Food needs to be tasted & seasoning adjusted as it cooks. Start slow, with small quantities. Allow that stew to cook a little while. Taste it-does it need a little more rosemary? Pepper? Add just a bit. Allow it to cook a little longer. Taste it…what does it need?

Yes, layering flavors takes more time than just putting it all in a pot & turning it on. But trust me-it’s worth it!

Here’s the same bit of advice from another person, with a little more detail…the food bloggers version of adding layers….

MAKE BETTER DISHES BY LAYERING FLAVOR

Layering flavor is a gourmet technique any cook can use. It’s all about combining, expanding and deepening flavors in a dish with spices, vegetables, meats, liquids and seasonings.

How to layer flavor
“Layering flavor” is a term that’s really in vogue thanks to a number of food television personalities. However, what, exactly does it mean and why is it important for making great food at home?
In many ways, layering flavor is something that everyone who cooks, from the chef at a five-star restaurant to the bachelor who can only make chili, does. Put simply, layering flavor just means that while building a dish, chefs add a number of different, yet complementary tastes beyond just the basic ingredients. For instance, it’s one thing in a dish to saute onions by themselves. It’s another to saute onions in a butter/oil mix with onions, leeks, shallots, white pepper and thyme. Both add flavor to a dish, but the second option layers in more.
Layering flavor has become a popular buzzword recently because so many chefs and cooks are going beyond traditional recipes and trying to build new and complex flavors into every bite. This is true for very fancy and for very simple dishes, which means that you have the opportunity to do it on any dish you might cook.
Of course, it’s hard to cover the entire breadth of layering flavor without surveying every recipe. We’ll cover some general concepts in layering you can use in many dishes.

Layering with seasoning and spices
The most important thing you can do to make your meals taste good is to season them well. Even if the recipe fails to call for it, anytime you add an ingredient, make sure it’s well seasoned. Vegetables that get sauteed, meats that get added, should all have, at the very least, a pinch of salt. A lot of chefs like to add a little black pepper as well.
Also, consider what other spices might work well in a dish. For this, you will need to keep the finished product in mind and think about how it will taste and which spices might build better flavor. When in doubt, add a little garlic as its earthy flavors can deepen a dish’s taste. You can also use stronger spices like paprika or nutmeg sparingly and only when you know it will help. Each additional spice will help layer in extra flavor.

Layering with vegetables
The choice of vegetables that go into a dish, even one where meat is the star, can often have a big impact on the final outcome. Therefore, be careful when you add vegetables that are not called for by the recipe. Even vegetables that might not seem to have a big flavor, like cauliflower or carrots, can radically alter the finished dish. However, you can usually add vegetables with similar flavors to those called for in a recipe and subtly change the dish without going too far overboard.
For instance, onions, shallots, and leeks are all used to add oniony flavor to a dish. Therefore, they can be substitutes for each other, even though the different types of ingredients all add something a little different to a dish. Red onions and shallots are sweeter. Leeks a bit more green in flavor. Vidalia onions are much sweeter. This is good, though. If you substitute or you use multiple types of onions, you will layer in new and unique flavors.

Layering with liquid
The choice of cooking liquid is vital to layering flavor because the right liquid can really affect the outcome of a dish. The rule of thumb when layering is, unless you are absolutely sure it’s necessary, never cook with water unless you’re boiling pasta. Instead, just about every dish can be cooked in chicken broth (for milder tastes) or beef broth (for strong flavors). Water is flavor neutral and can actually rob ingredients of their flavor. Broth, on the other hand, has its own taste that it can inject into the ingredients around it. Beer, soda, whiskey, etc., also can add flavors to the rest of the dish.
In fact, in some cases, you might want to hit your dish with a little broth, beer or whiskey even when the recipe doesn’t call for it. Do this only when you’re reasonably sure it will work, but that extra shot of taste can really layer in the flavor.

Layering with acid
Acid is a great way to add flavor, especially when it’s added in right before the dish is finished. Citrus juice is the most common form of acid one can add to a dish, though vinegar can also do wonders for some dishes. The nice thing about acid is that it awakens different parts of the taste buds (sour and bitter) that might otherwise lie dormant.
To layer flavor with acid, the easiest way is just to grate a little zest of lemon or lime into a dish and give it just long enough to cook so that the oils in the zest can cook out (usually a minute or so.) Just doing that will add a completely different flavor profile.

Source:
http://www.sheknows.com/food-and-recipes/articles/986377/how-to-layer-flavor