Just to add a few things here, and I so LOVE numbered points. But I should qualify this advice with a mention that I've only brewed about 8 batches so far, yet I already feel like I know a lot more than when I did my very first batch. So the veterans should correct anything that they feel needs it.
1) It's difficult to tell if you will need a blow off tube until it's too late. Things can seem hunky dory one minute and then 20 minutes later you come back to a mess. The odds are usually in your favor, I think, with most brews from extract kits, but if you have the time and resources then I suggest rigging a blow off tube as soon as possible. Make it once, you'll always have it. It's fairly common to rig one up using most of the parts from a 3-piece airlock, but if you do I recommend using an airlock that doesn't have the '+' plastic nub at the bottom (the narrow end that goes into the rubber stopper). If your airlock has one of those, carefully saw it off. The idea is to create a passage that won't easily get blocked/gummed-up that krausen can get pushed out of. If you don't have time/resources at present to make a blow-off tube, then putting the fermenter in your bathtub with the shower curtain drawn closed is a decent temporary stop-gap measure. However, if your house is like mine - the upstairs temperature where my bathtub resides is a bit too high for fermentation, whereas down in the basement is ideal. So you may want to risk a blown off airlock and mess in order to avoid high initial fermentation temperatures. Regarding temps -- when you pitch the yeast and during the most active fermentation (usually within 2-4 days of pitching) the temperature is extremely important. Most ale-yeasts prefer an ideal temp of around 62-73 F inside the fermenter (NOT the ambient room temperature which may be up to about 10F lower than the beer temp). Other yeasts will have different ideal temps. Go lower than the ideal temps and the yeast will slow down the fermentation process or become dormant altogether. Go higher than the ideal temps and you risk off-flavors. Once the most active fermentation is over, the rules on temp control (especially going above ideal temps) loosen somewhat.
2) Resist temptation as best as possibly to screw with the fermentation process. Sit on your hands and let nature perform its magic. Leave the house if you have to and go to the pub. With my first batch I almost set up camp and slept next to the fermenter in anticipation that something was going to happen. Other than the soothing sound of gurgling bubbles, nothing happened. If you desire a taste after a week or so, fine, but guaranteed it'll taste better after proper fermentation, bottling, conditioning, and then proper refrigeration. You also risk spoilage every time you tamper.
3) Bottling is an important part of the process. Be sure that the bottles are clean and sanitized. If it's the first time you're using the bottles and you and/or your friends or mother-in-law stuffed lemon slices, cigarette butts and whatever else in there, then be sure to use soap, hot water, and a bottle brush to get them good and clean. After first use, you can rinse them well with water immediately after use (night of, or next morning) and then sanitize immediately before bottling more beer. I highly recommend one of these - it's a great time saving device:
http://www.torontobrewing.ca/servlet/the-622/Jet-Brass-Carboy-and/Detail
3) Be sure to follow good procedures when you transfer to the bottling bucket. Avoid splashing the beer around at this stage as it can 'oxidize' the beer, which is rumored to make it taste like wet cardboard. It's important to have adequate lengths of the required hosing to avoid monkeying and frustration (trying to pull hoses off your siphoning system to then put onto your bottling bucket spigot and wand is REALLY frustrating). Calculate your priming sugar quantity very carefully. A small kitchen scale is another good investment and needn't be expensive - I got one for $10 and others may have gotten one even cheaper. You'll also find it handy for measuring hops and even grain when/if you go all-grain. Be sure to add the priming sugar to the bottling bucket before transferring the beer into the bottling bucket. This will ensure it's well mixed. I ruined my first two batches by adding waaaay too much priming sugar for carbonation. I then threw good time after bad by trying to periodically relieve pressure in the bottles in order to salvage what I eventually dumped.
3) Bottling the beer from the bottling bucket can get a little messy. I saw a tip on here that reduced the mess significantly: Set your bottling bucket on the counter above your dishwasher (if you have one) and then perform your bottling on the opened dishwasher door. If you don't have a dishwasher then a plastic storage container or even large flat tupperware container (such as for cup-cakes) might work well too. Spillage will collect on the dishwasher door (or in the container) and reduce the amount on your kitchen floor. Inevitably you'll get some, but it's a lot less.
4) Now that your first batch is conditioning, get another brew day underway so that your fermenter is once again full. You'll be surprised at how fast your first few batches go, and now that you're into the hobby, you'll likely be disappointed by the price and flavor of commercial beer. Work on getting your own 'pipeline' going.
5) Let the primed beer condition in the bottles for at least 3 weeks at about 70-75 F, but feel free to sneak a few tastes before hand. It's also a good idea to refrigerate the conditioned bottles for several days before consuming. The character of the fizz and head will be markedly improved if you heed this last step. Initially I thought that a few hours in the fridge, or 30 mins in the freezer would suffice. Yes, it'll be cold enough, but the carbonation doesn't seem to penetrate the beer as well, while the head was excessively large and frothy - like shaving cream.
6) After your first successful tasting, go to bed dreaming of larger pots, kegerators, blichmann burners and temperature control systems.
Last, I'll offer a small token of advice that i wish I had have known before I brewed my first batch. The 10 most important aspects of brewing beer are:
1) Pitching and Fermentation Temperature control.
2) Pitching and Fermentation Temperature control.
3) Pitching and Fermentation Temperature control.
4) Pitching and Fermentation Temperature control.
5) Pitching and Fermentation Temperature control.
6) Pitching and Fermentation Temperature control.
7) Pitching and Fermentation Temperature control.
8) Pitching and Fermentation Temperature control.
9) Pitching and Fermentation Temperature control.
10) Sanitation.
