Well all these guides are fairly helpful, yet I managed to find a cool web page to help find all the missions (locations of stones and objective points) http://wikicheats.gametrailers.com/Final_Fantasy_XIII_-_PS3_...
Not only do they have that but it tells you the best order to accomplish the missions in for success. As for other stuff they cover everything through a "Walkthrough" to "Side Quests" to "Battle Tips".
I hope this helps you out. I know it has been helping me.
Best of luck,