Hi C.,
I have two children - six and four. My six year old was a horrible sleeper and I didn't know so much about babies as she was my first. I was determined to make my son a good sleeper and he was! I ended up using two books, swaddling, white noise, and a less than ten minute routine.
I started with Harvey Karp's book, The Happiest Baby on the Block, and the 5 S system of sleep which includes swaddling. Swaddling actually replicates the womb by keeping the baby warm and their arms close to their body. I ended up swaddling my son for nine months using old sheets I cut up as he grew larger and too big for the commercial baby swaddling blankets.
At about four months I brought in Marc Weissbluth's book, Healthy Sleep Habits, Happy Child. My friends and I call this the bible on sleep. It gives you so much information on sleep and how it works, effects your body, etc. He has great information in there on how to get naps on track and how to adjust them if days get busy, etc. I still refer to this book and my kids are older.
The biggest piece of information that young was when to start the morning nap and how to create a under ten minute routine. I used to take him back to his room, make sure it was dark with the fan running for white noise, rock him, and read Goodnight Moon. Then I would lay him down or set him in his seat. I think at three months he was still sleeping in his car seat. He had horrible gas and it helped.
To this day we still rock, use a fan, and read Goodnight Moon. It is amazing how his body relaxes and he is ready to lay in bed. He knows I will leave but he is usually in the zone and happy to sleep. We can do this routine in any setting - hotel, Grandma's, etc. - which is nice, too.
Good luck! It sounds like your baby has a great momma!
Cheers, LA