I am in USDA hardiness zone 9b, and just planted store bought cauliflower and broccoli. This is the first time I am growing these (6 of each) in a raised bed and have no clue how to care for them for maximum results. I would appreciate a few simple steps from this group, in addition to watering (which is not necessary since it is raining)?
Other than preventing cabbage worms (see other answer), I'd focus on conditions. Cauliflower and broccoli both love nitrogen, more than is present in your average topsoil. They love freshly composted manure mixed into the soil they're growing in, but if that is not available, you can use a leaf vegetable/corn fertilizer at the three leaf stage, and then again when they're getting ready to head. Only water if it's necesary to do so (if the soil dries out). You don't want the plants to wilt. The faster and healthier they can grow, the better the crop will taste. Low water causes tougher, smaller, stronger flavored heads.
Cutworms can be a problem for young plants, and I've found great success in prevention, when I sprinkle fresh wood ash generously around the plant bases. This will also add beneficial nutrients to the soil. I've had some, but less miraculous success using crushed egg shells in the same manner.
A great way to prevent fungal diseases, to keep the plants clean for harvest, to keep all the weeds down, and to keep the soil constantly moist is to mulch heavily with grass clippings. I had enough to put a thick layer under my plants one year, and the top of the layer crusted over, but the soil stayed moist all season with no watering, and I didn't have to weed. I suppose chopped leaves could be used to the same effect, although they won't add nearly as much nitrogen.
And a tip for cauliflower (If you weren't aware): to get the heads nice and white like you can buy in stores, they need to be blanched. Otherwise they will be grenish brown and much stronger. Watch the plant closely, and when it begins to develop a head, about the size of an egg, tie the top leaves together to block out the light (example). Do this when the leaves are completely dry, as cauliflower are highly suceptible to fungus. In my opinion, broccoli is by far the more foolproof vegetable.
In my personal experience, the most important thing is to get row cover or some other insect barrier over them before you are visited by the white cabbage butterfly, which maketh cabbage worms. Since these are vegetative rather than fruiting plants, you don't need to let bees in, and you will be well served keeping the butterflies out.
I had never grown them here before, I'm not terribly close to other gardens, and the bleeping things showed up in no time flat (I knew that I should be set up to cover, but the spring went to heck for reasons unrelated to gardening, which impacted the gardening - so I didn't get them covered.)