My favorite is chicken/okra or seafood/okra gumbo.

Start with a Hvy deep pot, bottom covered with oil, med heat. Add Okra & a good pinch of salt, cook down, stirring often (okra will stick if not stirred often) till most all slime is gone. Then add water (1/2-3/4 pot full) & bring to a boil, then add roux (amount depends on my taste that day, hvy or Lt). Stir often till roux is disolved. Add chopped yellow Onion (amount depends on pot size? at least 2) Add Chicken & good smoked (La.) sausage cut in 1/4" pieces. If making seafood just add sausage now. You can now add 2 or 3 spoons of salt & black pepper & a few cloves of chopped garlic as well (to your taste). Place lid on pot & bring to a boil, then turn fire down low to a slow boil. Stir every now and then to prevent roux from sticking to bottom. Add water also if needed. While this is cooking chop a handful of green onions and parsley together. Save till later.
If cooking seafood: Once onion & okra has cooked an hr or so (onion is clear & tender), add cleaned raw shrimp, lump crab meat (we also like the whole crab claws when can get). Bring back to a boil & then turn down to a simmer. Cook until shrimp are done (30 min max) and turn off the fire. Then add green onion & parsley & stir, check for salt/pepper needed if any? place lid on pot and let sit 30 minutes to absorb flavors. Now add Tbl spoon or so of Filet' and cayane pepper if desire and stir. Bring back to serving temp if needed.
For chicken: Cook until chicken is near tender (slow boil) then add green onions & parsley as above, stir & let sit for 30 or more minutes also with fire off. After sit add Filet' and bring back to serving temp if needed.
Notes: If can find, use old hens (young cook too quick & fall off bone) good with squirrel or duck also.
Also I like to add a can of rotel tomatoes in my seafood gumbo when I add the water, is to your taste though? Gumbo is what ever you have or want that day.
Also, we hardly ever eat Gumbo without a side of potato salad & crackers.

Man, I might have to do that today !!!

Do a google for the folloeing title. This cookbook comes as close to true cajun cooking that you can get nest to the real thing.

Cajun Cuisine: Authentic Cajun Recipes from Louisiana's Bayou Country

For a ready made roux uses Savoie’s Dark Roux it comes in a jar and is made with just oil and flower i uses it when i don't have time to make a roux from scratch. As far as putting okra in it is all up to the taste of the cook i personaly don't like okra so i never put it in My famly on the other hand love shrimp and okra gumbo.

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Just my two cents