I got this recipe here. I adapted it a tiny bit and made a batch large enough to use a few times. I use all Penzeys spices unless specified. I like Penzeys because they are fresh and pure and they happily ship to APO's. (And NO, they are not paying me to say that. :o)
So, what you will need:
4 TBL Chili Powder - Medium Heat
1 TSP Garlic Powder
1 TSP Onion Powder
1 TSP Crushed Red Pepper
1 TSP Oregano
2 TSP Smoked Picante Paprika (not Penzeys)
2 TBL Cumin
1 TBL Salt
1 TBL Pepper
This taco seasoning has a medium spice kick to it. If you don't like it that spicy, cut down on the crushed red pepper and use a regular chili powder.
I use it both on beef and shredded chicken.
I even buy extra Penzeys spice jars with extra blank labels so I can store my homemade spices with my other spices. (I'm a freak like that.)