Catching Scaled Sardines with a Cast Net
The first thing I would do is find some Scaled Sardines. The closest consistent place to cast net scaled sardines is Culbreath Isles Flats (which is on the southeast side of the Howard Franklin Bridge). 4 feet of water is a great place to start. I can sometimes find scaled sardines at the small bridge on the Courtney Campbell Causeway on the southwest side as the water drops off from the shallow sandbar.
After getting some Scaled Sardines, I would start fishing the outside points of Double Branch and Channel A when the tide is moving out from those areas. I would wait until the outgoing is at least 1/4 started. On the opposite end I would follow the incoming tide back into Double Branch and Channel A. Fish the oyster bars that are now covered with water and mangroves before the water gets all the way back up and in. The fish will stage at the outside of those mangroves before the incoming floods all the way back. If the tide gets far up into the mangroves it will be much harder to get the fish out of the mangroves to eat. You can do it with heavy chumming with scaled sardines.
Using the right tackle.
It is a must that you use the smallest hook possible and the lightest fluorocarbon leader. I would start with a #1 or 1/0 hook and 20 lb to 25 lb fluorocarbon leader. The leader should be a at least 36 inches long with no terminal tackle attached (swivels,snaps, rings etc...). Using the smallest hook allows your bait to swim easily and will keep it off the bottom where there are many catfish. Especially in that part of the bay. You should also tie a loop knot to your hook.
Fish the entire water column casting down tide.
Now the grass flats out front, I would drift and use the same hook and leader as above. But I would also place a bait under a cork/float as to suspend the bait above the grass. Just make sure when you're drifting that your throwing your bait into or with the drift which will be down tide (the drift direction will depend on the tidal flow and the wind). You can use your engine prop and shaft to control the position of the boat on your drift. If cast your baits or lures up tide you will not cover the entire water column. Casting down tide with your drift will let you cover the entire water column.
Your line will be coming towards you at all times so you will be reeling up the slack. If your drifting too fast because of wind or tide, you can use a drift sock. If you hook a good fish on your drift, you can drop anchor and fish the potholes (sand areas with grass around it). When the fishing slows go back to your drift.
Don't spook the fish!
It is very important that if you are catching fish on your drift and you want to drift the same bearing line when you motor up to go up tide again, DO NOT RUN DIRECTLY back up the same drift line. Motor out and away from the line you just drifted so you do not spook the fish on your productive drift line.