Most gringos feck these up pretty badly. They are really easy to make well once you know the trick.
The secret is to make them two or three to a plate, not in a big casserole dish. Briefly fry your corn tortillas in some canola oil so they are just barely starting to get a bit firm, then take them out and let drain on some paper towels or better yet a wire rack. Stack them up so they don't dry out, and blot off any excess oil.
Your filling is up to you. Last night when I made these I added a little sauted chopped onion, shredded pulled pork, three chopped chipotles, a small can of green chilies, about 1/4 cup Mexican crema, and about 1/2 cup grated Mexican cheese. Mushrooms are great in them too, just saute them with the onions. Add your filling to your tortillas and sprinkle some more cheese on them. I like using the Mexican melting cheese for this, but jack or whatever is fine. Roll two or three on a single oven-proof plate, and if you make more just use more plates. If you want leftovers to make later, just freeze them like they are at this point, don't cook them. Don't add any sauce to them either yet.
Now, put your oven-proof plates in a 400 degree oven for about 10 minutes, until the tortilla shells are kind of crispy and firm. You'll see the filling bubbling at the ends too. Take the plates out and pour about 1/2 can of tortilla sauce (about 6 ounces) over each plate full of tortillas. Make sure the sauce has been warmed up first, I just put it in a Pyrex measuring cup and nuke it with plastic wrap over it, about 1:30 does it on high. Sprinkle more cheese on them, add chopped onions, jalapeños, olives, green onions, whatever else, and put back in the oven until the cheese melts and the sauce is bubbly. I like to pour on more Mexican crema or room-temp sour creme at this point too.
Then try not to burn your mouth skin off eating them.
If you freeze some for later, just thaw them out a bit and cook 2 or 3 to a plate as explained previously, then take out, sauce+cheese, melt, eat.
The good Mexican restaurants make them this way. They DO NOT cook them all together in a casserole dish like most gringos do. Just sayin'. And if you have the time to make your own enchilada sauce from scratch, well, that's even better.