Mistakes from my first brew:
Don't think that a six gallon brew pot is going to cut it. You need at least 8 gallons for a 5 gallon batch.
You're going to lose about half a gallon of wort from trub, equipment loss and hydro testing loss, so shoot for 5.5 gallons at end of boil.
LME adds a good amount of volume to the boil, so take that into account when you're figuring out your water.
You might lose about 1 gallon per hour of boiling to evaporation, but it's dependent on how vigorous your boil is.
Near-boiling water is 4-5% greater in volume than cold water.
Buy some good quality hi-temp silicon hose (1/2" ID) for transferring wort from the kettle to your fermentor.
If there's air in your drain lines when you begin to siphon or drain the kettle, you're going to have problems draining. Potentially big problems. Fill the hoses with a Star San solution before draining the kettle, and keep the other end of the hose in a catch basin. Once you begin draining, drain into the catch basin until it's obvious that all of the Star San is drained out and wort is flowing, then move the hose to your fermentor.
You'll also have problems if any of your hose connections aren't completely tight. Use hose clamps, and be sure to use the appropriate size of hose clamps, since bigger hose clamps won't clamp down on smaller hoses correctly.
Use distilled water with Star San. Don't use tap water. Makes the Star San last longer.
If you miss your OG, don't sweat it. It will still be beer. Probably good beer. Just take lots of notes on what volumes of water you used and what volumes of wort you ended up with and make necessary adjustments in future batches.
Buy two hydrometers so you'll always have one on hand in case one breaks on a brew day.
My first batch had quite a few mistakes but its all about learning. Im up to batch 8 and im still learning little things. Best of luck to you!
