Help making home brew traits

[GM and the Holograms]

I had an idea I thought would be fun for an upcoming campaign, but I need help implementing it. I want to make some home brew traits that will be assigned based on things that happen in the first session. I would start them with one trait, or two with a drawback.

Since these will be randomly assigned I'm hoping to keep them universally applicable. I don't mind if they're stronger than a regular trait, but not too much.

So if you have ideas tell me the trait name, it's benefit, and the circumstance that would lead to assigning it.

For example:
Watch and wait
+1 trait bonus on attack rolls, saving throws, armor class and spell DCs vs creatures with a higher starting initiative than you.
Assigned for having the lowest initiative in the first combat

[Lazaryus]

First Blood?:
Double your critical threat range for the first round of combat.
Assigned for landing the first blow in the first combat.

[Brad Whittingham 241]

Vigiliant
+2 trait bonus on Perception checks made to notice traps and hidden creatures.
Assigned for noticing a danger before it could act

Reactive
+2 trait bonus on Reflex saves made against traps.
Assigned for noticing a danger too late and successfully dodging.

Paranoid
+1 trait bonus on Sense Motive checks to discern lies.
Assigned for successfully discerning a falsehood.

Lucky
Once per day, you can re-roll a natural 1.
Assigned for rolling the first natural 20.

Tactical
+2 trait bonus to CMB when attempting the appropriate maneuver.
Assigned for succeeding a combat maneuver.