An oldie, but goodie. These pictures are from last Spring, when we were making the switch from bottles to sippy cups. As you can see from the pictorial below, it went over really well. (By the way, if you haven't yet noticed, sarcasm and I are quite close friends.)
So here you go - my step-by-step guide to introducing the sippy cup. If you're looking for real advice on how to make the transition, all I can offer is this: Just keep trying. It takes persistence. And patience. And maybe some humor.
Step 1: Show her the sippy. She's not impressed.
Step 2: Offer the sippy. Hysterics ensue.
Step 3: Try to explain it's still "milk" whether it's a cup or a bottle. Note the frantic signing of "milk".
Step 4: Cave in, make a bottle and resolve to try again tomorrow.