What skulls do you turn on to get better points?

Answer 1

All of the Gold skulls give the player a point multiplier, and each is as follows:

Iron

Multiplier: 3x, or 300%.

Effect: On Solo, restarts the mission upon death. On Co-op, reverts to last checkpoint upon death of any player.

Black Eye

Multiplier: 1.5x, or 150%.

Effect: Shields do not recharge, but must be accrued by beating (B Button on default settings) the enemies.

Tough Luck

Multiplier: 1.5x, or 150%

Effect: All of your enemies will dive with incredible success away from your grenades, plasma pistol bolts, needles and vehicle splatter attempts, and will have increased accuracy in all of these.

Catch

Multiplier: 1.5x, or 150%

Effect: All enemies with throw an incredible amount of Plasma Grenades with amazing accuracy.

Note: Makes game extremely difficult when combined with Tough Luck.

Fog

Multiplier: 1.5x, or 150%

Effect: The player's motion tracker is disabled.

Famine

Multiplier: 2x, or 200%

Effect: Any weapons picked up during the level will have much less ammo.

Thunderstorm

Multiplier: 1.5x, or 150%

Effect: All enemies are elevated to their next rank. (Ex. A Gold Brute would become a Chieftan with a Gravity Hammer, and a Blue Brute would become a Gold Brute.)

Tilt

Multiplier: 2x, or 200%

Effect: Enemy resistances are greatly increased. (Ex. The Brute power armor is normally pretty resistant to human weapons to begin with and fairly fragile against plasma shots. With Tilt turned on, the Brute armor is practically 100% resistant to any human projectiles and can only be taken down by plasma bursts.)

Mythic

Multiplier: 2x, or 200%

Effect: All enemies now have double their normal amount of health.