My problem has tended to be that after the beginning, everything goes too quiet and there is a lull or saggy bit until the story picks up again.
Over here green_knight is talking about beginnings.
For the record, here are some thoughts on the beginnings of my last few novels (all as yet unpublished):
The One About the War starts when Mark finds himself falling through the sea into another world. Various versions have started some time before the transition or on the beach with him being lured into riding the magical white horse. The latest version has him fighting uis way up through the water and struggling to shore. I am happy with this.
The one in desperate need of a new title begins when Matthew finds himself in a strange and different world (anyone see a pattern here?) and has had more beginnings than I don't know what. Also the mode of transition has been: a stone set in the earth; a magical gate leading into and then out of a ruined cottage; a magical gate leading out of a building as yet unspecified, possibly a modern factory unit. The version I posted for Embarrass Yourself As An Author Day begins some time before the adventure actually starts with some background and setting. If I ever came to rewrite this, I would have to decide whether this is necessary.
<href="http://helenkenyon.livejournal.com/413.html">Legacies of War</a> starts when Huw arrives in Arloros. He thinks all his troubles are over, but they are in fact just about to begin. I think that beginning is about as good a place as it could be. Can't be earlier because he'd just be trudging along the road. And if I start with the carriage crash (as a critter once suggested) the reader doesn't know about any of the characters and therefore probably doesn't care. I think it was at this point where I mastered the art of starting in the right place first time.
Moving a Mountain starts with the protags arriving to take up their new job and start their new life. It seems an obvious place. Again we don't need to start earlier and I think we need to see them arrive because that gives us their first impressions of the hostel, so it can't be later.
Revealing Secrets (WIP) did have an abortive beginning from some years ago that started far too soon. The female protag didn't actually get out of bed (*g*), but she was driving in to work, which was a whole 12 hours before the key event that drives the book. This was in order to get in information that I thought the reader needed. I've shuffled the order of things now, so the reader learns things after the killing and not before it. Only time will tell if this works.