I think infant sleep is one of those issues that is never truly conquered. Just as we seem to have it mastered, something else throws a monkey wrench into the situation. Lately, that is teething. But sometimes her schedule just randomly changes or we have things to do and her nap times get disrupted which throws off her schedule for a couple of days. Whatever it is, it makes things hard for both of us.
One book that our pediatrician recommended and we love in this house is “Healthy Sleep Habits, Happy Child”. I use it as my bedside reference on sleep habits as we move through the different stages with naps changing and/or disappearing, funky habits develop, etc. I highly recommend all new parents purchase this book and read it as necessary to conquer each issue as it arises.