Google "Tune in, bet pot, cash out" - it's a free e-book that's a good starter.
Also google "how to not suck at PLO the five commandments" - similar information presented in a different manner.
Lastly,
www.omahaplanet.com has a lot of good strategy articles on it but you have to be willing to hunt for them and sort out the advanced advice from the beginner advice on your own.
From my own experience moving from NLHE to PLO:
1. Be ready for a game that's ten times as much FUN in PLO - I thought NLHE got boring after awhile but your adrenaline is always stimulated during a session of PLO.
2. Be ready for the sickest, most humiliating and debilitating SWINGS that you couldn't possibly imagine beforehand. In NLHE, you can get AA all in and be about an 80% favorite no matter what the other guy has. In PLO you can flop top set on what looks like a dry board only to find out you actually have about 41% equity against two villains.
Good luck!
DTXCF