I have (nearly) no sense of taste and smell, and what sense I do have is heavily distorted. As a result, my senses are non-indicative of dish quality. Nearly every meal I cook is shared with at least one person, though, so I've had to adapt.
I iterate over the same recipe over and over varying the spice mixtures and ratios, and ask for comment every time. I write down said comments with the recipe, and then adjust from there. Usually my recipes stop evolving by the time I've written iteration #4-5 (less for newer recipes, as I can now "play" the flavors by ear).
When I'm cooking for people I don't see often, I use my well-rehearsed recipes. I also select foods where the cooking is more of a science, where it's hard to mess up the flavor, or where people take a self-seasoning approach (e.g. baking bread, grilling steak, baking potatoes).
Edit: Here's some simple spice trends from my personal recipes. These have been calibrated almost exclusively on Southern U.S. guests:
- Mild Spanish Paprika (Pimentón) is great for grilling and pan-frying pork (along with the usual suspects like salt and pepper).
- Add 1/person dried bay leaves (whole ones, not chopped or ground) and 1/person garlic cloves to your rice when cooking it. Remove them after cooking. Do the same for stews, and really anything that cooks in water (other than pasta and potatoes).
- Add some granulated garlic (which is basically powdered garlic without the dust issues) to nearly everything. It's quick, mess-free, and I think most people (at least near me) harbor a terrible addiction for garlic. Use actual garlic when doing stews, sauces, or you just have the extra time to peel it.
- Substitute bacon fat for butter when cooking things other than bread and pork. Only thing people are more addicted to than garlic would be bacon. Use both garlic and bacon fat when making mashed potatoes, watch them cry happy tears while they ask for additional helpings.
- Instead of plain vegetable/frying oil, get a bottle of non-virgin olive oil and a bottle of peanut oil. After cooking with them a few times you'll get a feel for which is right for each dish (rule of thumb: higher temperatures means peanut).
- I have yet to find a dish that wasn't improved by sprinkling some parsley on top at the very end. It adds color (specially to anything that doesn't have green otherwise), and everyone either loves it or is neutral to it.
To improve seasoning, any frying or searing will help. Frying chicken, searing steak, etc. Anything that has to do with heating oil. The things that can damage the seasoning are acidic mixes, and in long duration. An example: Simmering tomato sauce.
I would also like to add that actually seasoning the pan, and proper handling and storage will give you much better results in improving your seasoning. One good starting point is Kenji Lopez alt's advice on cast iron pans. There are other very good sources on this too.
Best Answer
My best recommendation is to taste as you go. Taste the initial product...raw vegetable, ingredient from the can, bottle, etc. and then continue to taste and sample a dish throughout the cooking process to see how flavors develop/diminish and enhance one another through the cooking process.
Learning to season food is a process of educating your palate and developing a "flavor memory"
One of the most important factors is to use enough salt. Food that is properly seasoned with salt shouldn't taste salty but will have a brighter more vibrant flavor of the ingredients that are in the dish. Food must be cooked with salt for this to occur. Food that is seasoned at the table will merely taste salty as the salt doesn't have a chance to dissolve and pull the juices out and help them mingle with one another as happens during cooking.
The more of the basic flavor profiles that you can incorporate the more lively and flavorful anything will be. Even before cooking you can take a look at a recipe and "disect" its flavor profile by determining which ingredients will add sweetness, sourness, etc. If you notice that it's heavy in one direction or another, the flavor profile of the item(s) missing will likely improve the dish. Then it's a matter of deciding what ingredient with that flavor profile would be best to add to that particular dish.
Shameless (but applicable to the question) plug: If you're ever in Savannah, GA I offer a class called "Flavor Dynamics". It is focused entirely around understanding how flavor develops, what affects our perception of flavor, and how to create well rounded flavor in your food.