I spent 12 years fixing MH-53s in the US Navy; I had to write a lot of brag sheets, and while I can feel your pain, I can't tell you exactly what to write.
1. be specific. Instead of saying "saved time for the shop by alphabetizing training records,"
2. put a monetary value on it. you can fudge the numbers a bit, just get close. Instead of saying "saved squadron money by re-using bird wash fluid to wash the hangar deck floor during duty weekends"
say
saved squadron estimated $400,000 dollars by re-using bird wash fluid to scrub 3000 square feet of hangar deck surface implementing weekend duty personel.
3. keep a record. Every day (or week) write this stuff down AS YOU DO IT, so you're not racking your brain the night before your brag sheet is due. You can't remember how many VIDS-MAFs you sign off after a few months, but you can keep track day to day.
So instead of saying "Signed off more VIDS-MAFs than anyone else in the shop"
you can say
"Signed off 124 VIDS-MAFS during evaluation period, resulting in 100% flight ops availability for 28 aircraft. bla bla bla . . .
I know this page isn't much help, but I keep seeing folks from Alexandria Va and other places searching "how to write a brag sheet" and ending up on my fiction writing brag sheet page, so I thought I'd drop you a note.
Honestly, if your supervisor is making you do a brag sheet on yourself, he's dumping what should be HIS (or HER) job onto you, but hey, that's the way it works. Slides downhill don't it? I used to have to do these for myself, and I made my guys do it when I made E6. Good luck out there, and keep up the good work, your nation is counting on you.
i know these examples are lame. I'm pretty sure there's no such thing as "bird wash fluid."