Cannot live in SE TX, next door to Louisiana, and not venture with crawfish. We experimented with two typical dishes which main ingredient is crawfish: Cajun boil and Etouffee. Both were delicious and quite simple to make. We are sharing our experience with the Cajun Boil.
This is an outdoor activity, for both cooking and eating. You will need a big pot, large enough to hold all the ingredients, a high BTU burner to ensure you can properly boil the water, and a lot of news paper to cover the surface you plan to use for eating. This is a "hands-on" meal and its is very messy but all worth it.
We boiled about 13 pounds of crawfish (about half a sac), enough to satisfy our cravings and use the rest for the Etouffee. 13 pounds of boiled crawfish will feed 8-10 people, depending on their hunger. 
We recommend using fresh live crawfish and the best veggies you can get.
For spices we used Old Bay and Louisiana brands. You can also use Zatarain. 
It is important to boil the potatoes almost to a done state, as the crawfish will be done only in 5-7 min. How much you boil the ears will depend on how soft you like your corn. We placed ours when the potatoes were half done. Total boiling time for the potatoes and corn was about 20-22 min.
Because you need to perform these tasks prior using the crawfish, it is very important that you keep your little critters nice and cool. We kept them in an ice box with ice.
Lastly, we added the crawfish and cooked them for about 7 min counted from the time the water boiled again. As they cook you can see them turn to a nice and bright red. You get to eat the corn ears and potatoes, which are great sides to accompany this dish.
Once cooked we scooped them out with the ears and potatoes, leaving the rest of the items in the pot. The liquid should be discarted.
You can add fresh shrimp, heads on, to the mix and make this a Seafood Boil too.
