After you do the initial mission, you will then be in Burramudgee Town. The town has multiple areas, each with many Opals. Walk into the Headquarters in the first section of the town, and it has many crates of Opals. Climb around and get them all. There will be metal crates that you cannot access until you buy a new "Smasharang". Leave Headquarters and go down into the valley below. There is a lake full of Opal bags, worth 10 and 25 each, and also one worth 200 Opals. After you get all of them, go into the next part of town. There are Opal bags and crates on every single building. The same is true for the third section of town, which has an entrance near a big fence. Search around the perimeter of all the buildings to get more Opals. There is a store owned ny Ty's parents in the middle town area. The first set of "Rangs" are sold there. Buy the Smasharang which will allow you to break open the metal Opal boxes all around. This will increase your take. Also, buy the Flamerang and Lasharang when you can afford them, which should enable you to get all of the Opals in this big town. Once you are done, you should have about 6,000 Opals. Save the game, exit to the menu, and reload it. All of the Opal bags and boxes will have respawned. Once you have the pattern down, it should take about fifteen minutes to get all of the Opals. Doing this will allow you to buy other "Rangs", Bunyip Keys, and Health upgrades early in the game.

When you start the game, dive in to the lake on the right. Go underwater and you will find an easy 200 Opals.

On the mission were you defeat Boss Cass, there is a bag with 3,000 Opals. It is at the very start. Take a couple jumps over the Uber Frills and Frills and punch through trees. You will reach a rock. Double jump to get on the narrow rock to get the Opals. You can exit the level and repeat this to get as many Opals as desired.

After defeating the Boss Cass in the last level, talk to the pilot who drives the ship. Skip the intermission sequences and get off the ship. Then, walk in a straight line and you will see a large pointy rock. Double jump to the top of the rock and get the 3,000 Opals. Exit the level and repeat the process. After doing this enough times, you will have enough Opals to buy anything in the game.

Repeatedly hit an enemy with the Lasharang to get more opals than just hitting them once.

When you start the game, go to the house to the right and search all of the boxes. You will find opals and the picture you are supposed to collect.