I'm opening up Sleep Week with what I know about sleep. Remember, none of these are unique ideas!
First of all, kids sleep the way they sleep. Most of it is individual personality. I thought that when I only had one kid, but now that I have two, I'm absolutely sure it's the case. There's only so much a parent can do to influence the way a baby or child sleeps, so you can stop feeling either guilty or smug right now.
Following from that, don't believe the "bad habit" hype. Think about it: If you had to switch job schedules so you slept a completely opposite schedule, you could do it if you had a week or two to make the switch. And you're a full-grown adult with years of sleeping experience and full-blown preferences. Babies are way more flexible, so they can certainly make a switch in sleeping styles/locations/times/etc. You just can't expect it to happen overnight. But given a week or two, you can make changes.
Therefore, in the first 12-14 weeks of parenthood you should take your lead from Malcolm X: By Any Means Necessary. If your baby only sleeps on your chest with his/her head wedged up into your neck*, do it if you can sleep that way. If your baby only sleeps in the swing or sling or Amby hammock thing or car seat or car or front carrier or laundry basket or between you in bed or holding onto the cat's tail or on the bathroom floor or in a tent in your backyard, do it. If you have to run the hairdryer, clothes dryer, white noise machine, "La Vida Loca" CD, or any other noise, more power to you. Whatever gets the maximum number of hours of sleep for the maximum number of people in your household, that's what you should do. And when anyone asks you how your baby's sleeping, just lie and say everything's great.
Once you're past that initial period, figure out what's happening, and what you wish was happening. Pick the thing that bugs you the most, think about what you could do to change that thing, and try it for a week. You'll either fix it, be on your way to fixing it, or realize your kid simply won't do that. If you're on your way to fixing your problem, keep going. Otherwise, pick a different thing you want to change, figure out how to try to change it, and try it for a week. Rinse and repeat. In a month or two your kid should be sleeping the way you want. Then a month later everything will change again.
Now, for the important principles of sleep:
1. Babies older than a few weeks can't stay awake during the day for more than a couple of hours at a time. (Apparently there are at least two sleep experts pretending this is a novel idea. It's not. Both of my grandmas know it.) If your 3-month-old seems chronically cranky, try putting him/her down for a nap two hours after waking throughout the day, and see if that helps.
2. Once babies hit 6 months or so, many of them will settle into a 2-3-4 pattern. That means that they'll take their first nap 2 hours after waking up in the morning. They'll take their second nap 3 hours after waking up from the first nap. They'll go down for the night 4 hours after waking from the second nap. Not all kids do this, but a surprising number of them seem to.
3. Despite what many peds say, plenty of kids still need to eat at least once during the night until they're a year old or older. There's no truth in the "s/he's x weight so s/he should be sleeping through the night" myth. OTOH, if your kids sleeps through the night on his/her own, don't wake a sleeping baby.
4. Most of the babies I know had sleep regressions at 4 months, 9 months, and 18 months. That means that no matter how well or how crappily they were sleeping, they'll sleep worse for a month or so at those ages. You can try to "fix" it or just wait it out--it doesn't seem to make much difference. You'll feel like hell anyway. And then they go back to sleeping as well or better than they did before the regression.
5. Teething sucks. And for some kids it really seems to disrupt sleep.
6. Someday your child will sleep through the night. I promise.
*And you thought your baby was the only one who liked to sleep that way at the beginning.