A lot of this is going to be trial-and-error, and it's going to take a little practice before you get it right. Me, I got good at it by making it once a week for over two years, and putting out an open invitation to my friends that there'd be red beans 'n rice at Chuck's place every Sunday (well, it was tough to cook on Mondays back then).
This dish holds a very special place in my heart. While I have many favorite dishes, and have had fabulous meals the likes of which come along very rarely ... this is number one with me. It's delicious, it's cheap, it's simple, and it makes me feel good. It's the number one comfort food in the world for me.
You'll probably want to fiddle with it each time you make it, and arrive at the exact, instinctual combinations of seasonings that you like. Feel free to alter this recipe to your taste, but don't stray too far.
[N.B. -- There's a bit of a texture issue here ... if you boil the beans by themselves first, and then add the rest of the ingredients and cook them, the beans will be very creamy, and falling apart, by the time the dish is done. Some people like this, but some people like their beans to be completely intact at serving time. If this is the way you like it, skip the first step of boiling the beans alone, and add all ingredients at the same time, bring to a boil, and simmer until the beans are done.]
Add everything else, and, if necessary, enough water to cover. Bring to a boil, then reduce heat to a low simmer. Cook 2 - 3 hours at least, until the whole thing gets nice and creamy. Adjust seasonings as you go along. Stir occasionally, making sure that it doesn't burn and/or stick to the bottom of the pot. (If the beans are old -- say, older than six months to a year -- they won't get creamy. Make sure the beans are reasonably fresh. If it's still not getting creamy, take 1 or 2 cups of beans out and mash them, then return them to the pot and stir.)
Serve generous ladles-ful over hot white long-grain rice, with good French bread and good beer. I also love to serve grilled or broiled fresh Creole hot sausage or chaurice on the side. Do not serve with a canned-beet salad. :^)
I like serving a few small pickled onions with my red beans -- I chop them up and mix them in with the beans. It's great! Why does it taste so good? As dyed-in-the-wool Yat Cherie Valenti would say ... "It's da vineguh!"