Take a Jungle Safari tour with Mr. Ung. You will see plenty of the main tourist attractions including animal shows, elephant trecking, awesome jeep ride to the top of the mountain and cool little waterfalls and statue gardens.
It should cost 1500B per person and includes a full day with lunch. Haggle the agent down as they will start at 1800B typically.
Do this as a starting point to see the main things then get your map out and explore the rest of the island!