Successfully complete Chapter 4 in Story mode offline to unlock Extra mode.
Successfully complete the game by defeating all forms of the final Boss to unlock new voice options when creating a new cast character.
Successfully complete the timed missions in a chapter with an "S" rank to hear an audio preview of the next chapter when the current chapter ends.
Go to the shop and buy a lot of the same weapon that you use. Then, add them all to your palette. Equip all of them with skills, if desired. This trick does not require multiple skill items. This will save a lot of Meseta because you will not need to buy Photon Charges. This trick is also very effective for forces because they will not run out of photons nearly as often.
The more missions you have completed in Story mode, the more that become available in Extra mode. From level 1, you may level up your character to level 10 or so by simply repeating the first mission from the Flyer Base on Parum, "Creature Discomfort". This will also give you a chance to build up a supply of Synthesis items, Star Atomizers, and Scape Dolls if you break open the correct boxes. After reaching level 10, go to the shops on the various planets and look for the best items and discs. If you have already completed the first six missions of Story mode, you will be in good shape. For Rangers, two Blasters, two Compadri, and two Ortotore/Bastara Combinations are recommended. For the Photon Arts, Ice Elements are recommended, as they are widely effective and Freezing is a useful status, and to switch the elements for your second weapon according to the current situation. Continue fighting until you reach level 15, then do the mission from the Parum Flyer Base "Ruler of the Plains" for experience. Have half of your weapons set to Ice and the other half for Grav if you are a Ranger. All Koltovas and Flying enemies here are weak to Ice, and the Vahras are weak to Grav. The De Ragan is also weak to Ice. To take him down easily, aim for the base of his neck or head with your weapons. However, if you are a Ranger, an Ice-equpped Blaster or Compadri works best. If you get an "S" rank on this mission, you will get 1,500 Meseta, 60 Mission Points, and a De Ragan Room Decoration that sells for 5,000 Meseta. For defeating the De Ragan, you will receive 1,440 experience points. Since there are twenty five total enemies in the mission each giving about 40 experience points, you will end up with around 2,440 experience each trip. Continue this until you are about level 25. After reaching level 25, upgrade your weapons (either buy new ones or use Grinder C+3s that sell for 1,500 Meseta from the Items shop on them) for extra power. With a C+3, there is no chance of upgrade failure for the first two times. You can safely upgrade all your weapons twice. Next, go back to Parum again, and then go to the Linear Train Platform in the G.R.M. shop area. Make sure to Photon Charge and save, then take the Cargo Train Rescue mission. This mission is difficult to get an "S" in, but is also worth it. All enemies are either weak to Ice or have no weakness. Enemies here give more experience points, and if you successfully find all 32 enemies and finish in under seven minutes, you will get an "S" rank. If you get an "S" rank on this mission, you will get even more Meseta, mission points, and another room decoration item that sells for 5,000 Meseta, as well as an Extra Slot item for an Armor.