When you get to the part where there is something to jump over with two bottles on top, shoot or drink them. Then, reload the checkpoint to drink or shoot the bottles again. They will count towards your totals and allow you to easily get the achievements or trophies associated with them. This doesn't work with the blue flying insects or the news bots.
At the very first area on the ship, just after the opening sequence, a door will malfunction with a semi-circular flashing red light. After a crewmate tries to fix it, three red lights will appear in a ring around a dot, referring to the same error status of the Xbox 360 "red ring of death".
When low on Peacemaker Carbine ammunition, press SQUARE to instantly refill it at no cost. This is useful when used in Boss fights, saving you costly ammo when you can keep refilling your rifle. This also does not cost any Skillpoints.
The following is a very time consuming way of racking up skill points:
Just after you and Trishka separate from Ishi while on your way to meet the General, you will reach an area with a dropkit, newsbot, and a metal sliding door. Open the door. There will be a street with a bus that you need to leash into a gap to cross. Continue fighting until the Mechaton's tails smashes a barrier that allows you to continue hopping over a cement barrier. Approach the barrier, but do not hop over it as you will not be able to go back if you do. When Trishka is standing next to you by the barrier, run back to the room with the dropkit and newsbot will have respawned. While running back to the room you should see the game pause and display the loading symbol in the bottom right corner of the screen jsut before you cross over the bus. If you do not see this then go back to the barrier and let Trishka catch up to you. The newsbot will respawn indefinitely giving you unlimited skill points at 500 points a kill. After killing newsbot return to the cement barrier and allow Trishka to catch up to you. Repeat the process as many times as desired.