Enroll in a Japanese class at a local community college or Japanese cultural center. Greetings are generally the first thing that are taught in any language course, so you will be getting off to a good start with your project.
Watch YouTube clips of Japanese greetings. Pay particular attention to the way the native speakers move their mouths. This is the way hearing-impaired people learn to speak, and it is a very effective way to help you pronounce the greetings properly.
Hire a Japanese tutor. Record your lesson so that you can review it at home. Ask her to recommend additional resources she thinks will help you learn the greetings.
Talk out loud to yourself. Stand in front of a mirror and practice your Japanese greetings. This exercise will also help you evaluate how you will come across to a native speaker.
Record yourself saying the Japanese greetings and listen to your intonation. Often, what you think you sound like isn't what you hear when you listen to your recorded voice.
Concentrate on pronouncing your Japanese greeting clearly. If you mumble your words, people won't be able to understand you.