Putting my first brisket on the smoker in a few hours and need to know whether to put it fat side up or down. The web doesn’t seem to be in agreement. It’s a 5lb brisket and the fat layer isn’t incredibly thick. I have a propane smoker so the meat sits directly above the heat.
Thoughts? Tips to not ruin this thing?
Directly above the heat, I’d say fat side up. There are arguments to and fro, some foil the brisket once it reaches max temp, as well.
Up
Up… you want that fat to drip down over the meat.
Down gets my vote. IF the heat is directly below the brisket, it might dry it out from the bottom up without the fat shield.
Up. Even directly over the flame you want the fat to permeate the brisket, not just drip off and flare up.
When Birdman and I first started smoking we wanted to know if brining the pork would have an appreciable effect on the final product, since the cooking process is so long. So we cut it in half, brined one half, and smoked them together. Turns out brining did make the pork better.
So, my recommendation? Cut it in half, smoke one half up and one half down, and see which you prefer. 
Ah, more barbecue voodoo.
I do up now, but I’ve also done down. It makes no difference so far as I can tell. I usually flip it at least once during cooking, although I’ve also done it (not on purpose) when I didn’t get a chance to flip it and it turned out beautifully. So, honestly, it’s hard for me to separate superstition from culinary science.
Tips for not ruining the thing: If it’s a 5 pound brisket, I assume all you have there is the flat? The flat can be tricky on its own. Brisket, in general, is a little more finicky than most other barbecue meats (I’d consider it the most difficult to barbecue consistently well). It’s easier to cook when its in its whole form (aka “packer cut.”)
I’m generally anti-foil, but this is one case where I may foil after a few hours of smoking. I have no time guidelines for you. Brisket is done when it looks and feels done. Generally, that means finishing in the 190F-200F range temperture-wise, but there is also a characteristic “wobble” one looks for on a whole brisket when it’s done, as well as the fork test (fork should slide in pretty easily; however the fork will slide easily in overcooked meat, too. Brisket should be soft and tender, but maintain structure. It shouldn’t fall into pieces.)
This tutorial looks like it covers the subject pretty well, from a quick read over it.
Up. Cook in a foil bowl or pan. Remove excess liquid every hour or two.
Best brisket I ever made: I took it out, let it sit for a while, then grabbed my slicing knife to cut it up. I had the knife upside down for the first cut, and it slid through the meat just as easily as the sharp side. Long and slow does the trick.
Went fat up on the smoker for 4 hrs and am now bringing it up to 185-190 wrapped in the oven. Smells good and looks good so far.
Here is the recipe Im using http://allrecipes.com/Recipe/davids-mesquite-smoked-texas-brisket/detail.aspx
How can I tell if I have just the flat or a whole brisket just by looking?
If it’s 5 lbs, you don’t have a whole brisket. A whole brisket is usually around 10-12 pounds. When it’s split, it’s cut into the flat and the point. The flat is the leaner and, well, flat. The point is fattier and more round compared with the flat.