A hard-shell taco can break apart in your hands after just a couple bites if you're not careful. The trick is to hold it the right way and take bites from both sides as you go.
In the diagram I've drawn above - inspired by Mark Richt's sandwich-eating philosophy - you'll see my preferred approach to the crispy, crunchy treat whether it's from a fast food chain or a sit-down Mexican restaurant. Start by holding the taco near the center with your fingers applying pressure just along the "meat line." If you hold any higher, you run the risk of snapping the fragile shell. If you hold it any lower, you won't be able to grip the taco from above, like I do.
Take your first bite at the end of the taco. I recommend the classic "taco neck" method. Then follow up with the next two smaller bites labelled above, making your way toward the center. Now, spin it around and repeat the process on the other side. Eventually you'll be left with two big bites in the center, and the shell should still be intact. Enjoy those last few moments of tasty taco bliss. Alternatively, if you take really big bites, you can replace 2 and 3 with just "2," replace 4 with "3," replace 5 and 6 with "4," and replace 7 and 8 with just "5."