It's a real challenge to cook a nice flat so don't beat yourself up too much. Lots of great cooks will end up with disappointing flats at times - from over confidence or too much beer, etc.
Here are some things I suggest:
1) Make sure you get the best brisket you can afford. Wagyu would be awesome. I consider USDA Prime a minimum grade. Choice if that's all you can find.
2) Build a nice gentle fire with a nice gentle draft. You do this by using more wood splits while using less air flow. This takes some practice. Build the fire close to the firebox door and far from the cook chamber. Use your dampers.
3) Set the brisket in the cook chamber as far as possible from the firebox, but not too close to the far bulkhead. You've got a reverse flow, so be sure you understand where the hottest part of the cook chamber is and try to avoid it.
4) Set it in the smoker in a way to protect it from radiant heat. You've got a reverse flow, so you should have that problem solved automatically.
5) Set it in the smoker in a way to protect it from convective heat. In other words, place the large fat point end towards the blast of hot air.
6) Stick probes in both the point and the flat. If you have only one probe, put it in the flat.
7) Consider the foil boat method when it hits the stall since this is when the juices start to sweat out of the meat. High and tight.
8) I would wrap it completely in butcher paper at 185 or so. Then put it back on for a short while.
9) When to pull it? Depends on how long you are going to hold it or rest it. It's okay to pull it a little early if you are going to give it a loooooong hold. But a short rest, like two hours, you pull it when it's soft underneath. You can feel it with your finger tips. You should rest it at least two hours. The longer, the better.
These things should give you a pretty nice flat.
Above is just MHO.
Good luck. :-)