Hihi. First, I think the best build is 25 in SPR and all the rest in INT. I also think that is the opnion of most of the mages on this forum.
As for skills go, it dpends. A lot of us live off our our MM1, so I put 5 points inot cooldown and 5 points to increase power of Magic Missile. If you look in the wiki under mages, there is some really good advice on whixh skills to empower and how. Also, if you go to the Guides section of the forum, Yosei recently made a guide for mages and it has some great advice with her build and her skill empowerments listed.
I'll try to find you the link.
EDIT: Here ya go. Read this thread, it may help you out a lot.
http://www.fiestafan.com/forums/showthread.php?t=4154