Presumably she was quite an easy baby?
DD was easy to sleep train because she was (i) a great eater who could have lots of milk during the day (so I knew she didn't need to feed much during the night) and (ii) she was big (consistently following the 95th percentile curve) and some people (including health care professionals) believe that larger babies go through the "four month sleep regression" and adopt adult-like sleeping patterns earlier. She was not easy in any other instance - e.g. she had a really bad acid reflux when she was 6 weeks and I had to argue with GPs to get the right prescription. Once DD was put on medication, she got much better and I could focus on her sleep.
Also, DD has always been very loud and noisy and, ironically, it helped with getting her onto a routine. She used to become cranky as soon as she was getting mildly overtired so I could not really miss her cues.
Did you let her decide the routine or did you follow a book?
I had a great maternity nurse helping me for the first couple of weeks (couldn't afford her for longer). I relied a lot on her advice and tips. I have also read lots of books - the most useful was probably "Baby Whisperer" by Tracy Hogg. She gets bad press on Kellymom but her recommendations on baby sleep are highly effective. Of course, all books are only guidelines - I only used what I thought was useful and relied a lot on trial and error.
And was she on bottles not breast and still doing the 3 to 4 hour feed?
Yes, I formula fed. DD was on anti-reflux milk (which worked well for her condition).
2 hours awake sounds a bit long for mine, she can do about 1.5 hours. How did you manage that?
Here I was completely baby led:). I followed a version of EASY (wake-eat-activity-sleep) routine until DD naturally extended her awake time to 90 minutes - 2 hours. She could always stay awake for longer in the morning when she was rested. If your DD can only do 1.5 hours, I would just go with it. It is much harder to settle an overtired baby.
Good luck!