Depends.
If you have a good ranged opponent like anivia or Kennen , max out
Q,E,W
If you are laning vs Akali , Katarina or Ziggs ..etc go
W,Q,E
About build , go glasscannon with rylais and/or RoA . If you Build her too tanky she wont be able to do much dmg without her full combo on.
Plus that her W counts as One target spell ;)