O’ahu is a beautiful place to live! I lived there for 3 years and it was amazing! Cheers to you!
When I lived there, I looked for apartments in the following newspapers (or online) Honolulu Advertiser, or Star Bulletin. I would also check out Craigslist.com. The commute from the east and west sides are pretty brutal if you plan on working in town (Honolulu). So, definitely Honolulu is a good start. Good luck to you! Write me if you need anything!