Quick Money
Blow up the trash around the level (oil cans, old cars, old buses, etc.) and earn some easy New Yen. Shibuya is a good level to do this in, because it has a ton of trash. You can blow up the cars twice.

Free Cash
On the main navigation screen, rotate the Right Thumbstick clockwise. This will rotate your icon. Each time they complete a revolution, you will earn 100 New Yen. You can earn up to 1000 New Yen each day doing this.

Better Mechs Upon Game Clear
Once you beat and save your game, mechs that appear on days that are not divisible except by itself (i.e., days that are prime number days, like 2, 3, 5, 7, 11, etc.) are super-powerful.

Secret Super Weapon
If you upgrade an Aeron 25mm minigun to level 98 heavy (at a cost of around 220,000y)its attack power raises to about 1000. If you raise it one more level to level 99 heavy, its attack power will be 17,525 but it will cost 6,700,000y. It's ammo capacity decreases from 94 to 6 but one shot should destroy any sv.

Stocking The Good Mechs
Visit any of the mech stores on any day that is numbered a mulitple of 6 (6, 12, 18, 24... etc.). The mechanic in the center of their selection will be a different color from the rest, and it will have hocked-up and powerful weapons!

Skip Intermissions
If you want to skip any intermission sequence, hold L+R and click both analog sticks.