My First Brisket. Tips???

This thread should supply more than you will need. 

http://eggheadforum.com/discussion/1194980/memorial-day-weekend-brisket-cook-whos-with-me-rules-are-simple

Butts always stall around160 and the stall can last for hours, that is normal. The same for brisket. Good luck!

A couple things that you can do to get through the stall is either wrap it in foil or buchters paper to help speed up the process or take you temp up 25 to 50 degrees more to get through it.  By the time it goes into the stall it should be above 150 so taking the temp won't hurt and you will still be in the smoke zone.  Also triming the hard fat off helps in the cooking process

The first step is to source a whole "packer" brisket.  I see you are in St. Louis. I am pretty sure that Costco carries prime packer briskets in your area. I recall @Stlcharcoal posted a picture of a bin full of them. There are other vids for cooking and slicing. 

Here are some tips on selection and trimming:
https://www.youtube.com/watch?v=VmTzdMHu5KU

Best tip I have for you is to read, read and read some more.  Not just on this sight (although everything is probably here).  Watch videos on youtube.  The more you know the less you'll panic when something unexpected comes up.  And IT WILL.
I wouldn't cook it at 225.  I'd go 265 and make sure you monitor the temp in the thickest portion of the flat.  Start it early....hours early so you can FTC the meat for at least an hour (or up to 6) before serving/slicing.
Don't stress!!!  It's only BBQ.  Have fun and enjoy the process.

Can't wait to hear how it goes and see the pics.

In addition to what has already been said, the most important thing I learned is to be patient. If you have a set time you need/want to be eating, give yourself 3-4 hours before that time for the brisket to be done. Wrapped and in a cooler lined with towels the meat will stay hot for a very long time. Last thing you want to be doing is trying to push things to get it tender, or worse, pulling it off before it's done, because guests are ready to eat. 

What's the cook time on one of these? I know every one is different but looking for an approximate. I just picked one up to try for my first this weekend as well. It's about 6.5 lbs, so just a lil guy- that way the expense is minimal when it goes awry. Thanks all and sorry to OP for high hacking. 

@chuckytheegghead - as above, every hunk of cow is different but you are definitely in the ball-park with @dsrguns estimate.  They key with a flat is to keep it from drying out.  Many here use Dr BBQ's recipe with foil and a liquid (coffee I believe) add at around the start of the stall.  Give the forum search function a look, many threads.  Regardless of foiling the entire flat, I always foil the thinner end of the flat to help reduce the drying and cut a notch across grain before you start the cook so that when the meteorite is formed you know the slice direction.  And only slice on demand as it will dry out before your eyes.
BTW- around here the cost of a packer (prime grade) / lb is around $3.00 and the cost of a flat (choice grade)/lb is around $6.00.  Thus you can get double the quantity (minus the trimming on the packer) for about the same price.  
Given your first go-round I would look at foil and beef broth or the above mentioned DR. BBQ recipe to ensure a great out-come so SWMBO will let you go again.  Enjoy the cook and eats. 
Hi-jack apologies here.

I've added mine to eggs for breakfast and also heated up in a pan with some beef broth for sammiches. Flats can be tricky as it is much leaner than a packer cut with the point If you are able to try a whole brisket next time. The point is fabulous..As lousubcap and I concur, no burnt ends.

If you like chili and it isn't too hot for it already wherever you reside then I would highly recommend you search @EggObsessed award winning smoked brisket chili. It's incredible! Burnt ends are always a crown pleaser around here. Or nachos.