With the exception of a shrip or crawfish boil or oysters, most Cajun cooking revolves around rice. Here's a hint when using rice. Add it to the other indgredients before you add the stock or water. You want the rice to absorb the flavor before it boils.
Here is another hint. Most rice dishes start with a roux. The roux should be the color of a copper penny when you add the rest of the ingredients. Jambalaya, gumbo and Etoufe all start with the trinity-celery, onion and bell pepper. After that, you can add whatever you want. Gumbo is not cooked with rice. It is served over rice. Gumbo is nothing more than jambaya soup, served over rice. The same is true to some degree about etoufe.
A couvillion is fish sauce and it can be done with kind of fish. You simply boil fish parts and add a little thickeing and seasoning, making a gravy.
Diry rice, a staple for all Cajuns, is simply hamburger and chopped chicken livers mixed with rice and seasoning. My dirty rice is world class. I sometimes mix my hamburger with some ground pork. :)
The easiets thing to do is a shrimp or crawfish boil. All youo need is a big pot, a big cooker and plenty of beer. And know how to season it. I have never found anything better than Louisiana Crawfish Boil. It is a powder and the best I have ever used. The key is, when you take the crawfish or shrimp out of the boil (20 minutes max) they go into an old cooler and are sprinkled liberally with the powder. Then seal the lid for 20 minutes. Be carefull not to overcook crustaceans. It is easy to do. You want them firm and they will continue to cook after you remove them.
This is the cooler I use to "season" my crawfish. This is 50 pounds. The corn and onions have been removed.