You may want to try using Flash SharedObjects
I used this method when saving data to an iPhone and it worked well. It's fairly easy to get started with and it writes in the application specific directory on the phone (or app data on windows).
It retains an 'object' type so you can reference items you store through normal object referece ie. myStorageObject.data.username, myStorageObject.data.score etc, (assuming there is data).