Definitely get a good book like the one the last mom mentioned. You'll be referencing it for advice for months to come, and you'll pull it out again for each child you have.
Meanwhile, the main thing to remember is that an over-tired baby will not sleep well, and you'll get in a vicious cycle of crankiness and sleeplessness. It's also important to note that you won't get a REALLY regular sleep pattern until she's about 12 weeks old or about 12 pounds. The 12 pounds thing is really true -- my daughter and son both slept 8 hours in a row at 12 pounds, for her it was at 15 weeks, for him it was at 8 weeks.
At this point, the routine is as much for your sanity as it is for her sleep habits. One thing that really helped me with my second child, who was a screamer, was to focus on the amount of wake time rather than sleep time. Why? Because he didn't show a lot of sleep "cues" until he was already over tired. He'd go from apparently happy to screaming like a banshee before I knew what hit me. It was then I learned to A) watch him more closely for signs of tiredness, and B) that even though he seemed happy, if he'd been awake for an hour, I had to tear myself away from the little darling and put a perfectly happy baby in his crib, even if I just wanted to keep holding and cuddling him. I think we're sort of programmed to "leave well enough alone" and keep stimulating, holding or playing with a baby just because they seem to be enjoying it, and we don't take action until they cry. Often, the cry is the LAST stage of sleepiness. By the time they cry, they are desperate!
At 8 weeks old, she shouldn't be able to stay awake more than an hour or so most of the time. There might be one part of the day where she's awake and alert for close to 2 hours, but that would be an exception rather than the rule. There may even be plenty of times where she's only awake for half an hour after she eats. That's fine too.
First, pick a morning wake time for beginning her routine. If she naturally wakes at 5 for a feeding, start there. Once the routine is in place, you can push that time a little later. From there, encourage a cycle of "sleep, eat, awake" that is about 3 hours from the beginning of one feeding to the beginning of the next. This might mean she'll wake at 5am, take a bottle (or nurse), coo and smile at you for 20 minutes, then sleep until 8am, take another bottle, watch you eat breakfast, watch the news, then sleep from 9 to 10:30...etc., etc. From what I learned with my two and swapping sleep stories with other mom friends is that the 3 hours is more of an average rather than a hard rule -- especially if you're nursing. My son might go 2 hours between feedings in the morning, 3 hours between the next two, take a whopper of a nap in the afternoon, thus going 4 hours or so between feedings, then 2 hours, then feed at 7, 8 and 9, then sleep from 10p to 7a. The thing that WAS consistent (except for fedings after 7pm) was the sleep, eat, wake cycle.
Good luck!