Personally, I used the Wireless Java, Second Edition book from Apress and started coding in like two days. There is a new third edition out, unofrtunately, they didn't get as good a review as I had given for the previous version. I don't think much has changed though? Shrug.
There are some really nice tutorials at java.sun.com on the J2ME page.
The other thing to find out is what versions and APIs your phone supports. Unfortunately that is difficult from the vendors materials, since they don't care. Just Kidding. The vendor should have a developer website that will tell you, or it might be on the list of devices at Sun's website. Look to the left menu to find that page.