The base around which every taco seasoning recipe is built is chili powder, paprika, and cumin. From there, many add onion and garlic powders, salt, or flakes (if you use salt, decrease the amount of additional salt you add). Some add other spices and herbs like Coriander and oregano for interest and most add at least one additional type of pepper either in the form of red pepper flakes or cayenne for heat. If you want smokiness, you can add smoked paprika (a favorite of many chefs) or chipotle. Personally, we like to add a bit of flour and or cornstarch. This seems to give a little body to your taco meat and makes the seasoning act more like a sauce that coats the meat. You will want to add a small amount of water at the same time you add your seasoning if you include flour or cornstarch.
My Go-to Recipe is:
Like I mentioned before, you should adjust this recipe as you like based on your own personal tastes and preferences. Here is another great option from one of my favorite TV chefs, Alton Brown.