Quoting K.MarieAnnette:" how did you get him to really start using it?"
Well my son was the same way at first! He started trying to drinking out of my water bottle (which has a straw) around 5 months. I decided to buy him some sippy cups then. He wouldn't hold it up on his own for awhile but he would pick it up and drink from it occasionally. I would put water in it at that age. But I really started giving it to him on a regular basis around 8 or 9 months and I would give it to him everyday to try and drink out of whenever I would feed him baby food. I would give him watered down motts for totts juice in it.
I think giving it to him every day helped get him use to it and now he drinks out of them fine. He is 12 1/2 months and he doesn't use a bottle anymore either! Some of them he wont drink out of though, so you kind of have to find which one your baby will like. I would buy maybe 1 of each and see which one she prefers!