Hi
1. Be consistent...it will come
2. Maybe try a straw cup? Both of my kiddos started with those and took to it almost right away.. and then transitioned to regular sippies within a couple of months.
3. This is just my opinion....I would only offer milk in the sippy until they get the hang of it. A lot of times you end up with the problem of they won't take milk out of it.
4. Try taking the valve out until they "get" it. Or there are some cheap sippies at Wal-mart that don't have valves
5. I think Tracy recommends sitting behind them and help them hold it (bringing it to their mouth and tipping it up) so they can "see" how/what to do.
6. Try a regular cup or other type of sippies
HTH