Carry a torch or even two in your nav bag. Carry spare batteries (in fact if you carry a GPS then make sure to get a torch that will take the same batteries). Carry a $2 glow in the dark bracelet available at Coles.
I'm not advocating rule-breaking but it it very wise to remember that an aeroplane will fly overweight but it will not fly without fuel.
A pilot of similar or lesser skills may have made it in five minutes before you arrive but it doesn't mean that you will too.
Learn the value of navigating around storms forming an equilateral triangle with your FPT and TMG. i.e. If you've got no GPS and you're tracking 000 and there's a storm you want to avoid by going left of it turn 60 degrees left onto 300 and note the time then when you're sure you will clear the storm turn 120 degrees the other way onto 060. Once you've travelled for the same amount of time (and barring any wind) you'll be back on your FPT as if you'd travelled exactly 1/2 the time (so you should know where you are).
If you do something silly and record it don't post it on youtube or facebook or even email it to friends.
Save the local BOM RADAR url in your phone (and don't bother with anyone but Telstra; it's a ****house setup but it's a lie if anyone says that they can give you 99% of Telstra's coverage).
Get practice at killing flies and try to clear them from the top of your instrument panel just before take-off (when it gets noisy they will go straight for your nose).
When loading passengers scare away the flies from their backs just as they enter the aircraft. (You won't get them all but enough will fly in so why carry them on your passengers backs too?)
Keep two small tins of tuna in your nav bag (good energy in a small-ish package).
ALWAYS REMEMBER to follow the advice of your CHIEF PILOT (unless he or she is a dodgy prick... safety-wise).
~FRQ CB
PS I'm serious about the flies.