+1 on the grey matter bieng the only line of defense.
Everything else is just there to minimize the carnage, if you screw the pooch and have a brain fart.
Husky Forrestry Helmet w/ears and mesh screen.
They aren't quickly adjusted, but once set there's no need to fuss.
It actually helps keep your brain wired to what you're doing.
Your ears not getting pounded, and crap not poking you in the face and eyeballs while cutting and moving around, frees up more attention to be directed at not doing something stupid. Limbing in a thicket with blackberry canes flailing around sux if you keep both hands on the saw where they belong, but less so if your eyeballs and nose aren't getting the "Slap chop" treatment.
GOOD eyepro.
I like Oakley M- frames, but other good eyepro works just as well.
Keeps the fine crap outta the eyeballs, and will reduce the damage/pain from larger high velocity bits.
If you're cutting while blinking out loose dust, you're really just running a friggin chain saw with your eyeballs closed..and distracted, with crap potentially falling on you.
Think about it.
Chaps.
I'm currently running a pair of some seriously Rancid Husky Full wraps, but new and clean models from other makers are good too.
I like 'em, and they make sense if you're not a blithering idiot.
In the winter, they are warm and insulate when kneeling in the snow.
They are great for waddling into a tangle of Greenbrier and Multifloral rose to drop a snag. It's hard to concentrate on felling safely when you're bleeding to death from a thousand thorn lashes, and if you ever have to unass the back cut because of a blowout, you can run through thornapple as fast as Hussein Bolt and not come out looking like a bad Cole slaw.
Ever see a skeeter bite though 5 layers of Kevlar?
One less distraction.
Most times when I have screwed up and gotten mangled doing anything, just a little bit less attention and I mighta gotten dead, a little more and I woulda just needed a band aid.
The lid, eyepro, screen, and chaps allow more attention to be given to the task at hand, and buys a bit more room for peripheral awareness to other hazzards that are ALWAYS there.
Chaps, eyepro, helmets, screens are NOT gonna stop a monumental #### up from killing or maiming you. They will however aid your brain in avoiding the MFU in the first place.
Stay safe!
Dingeryote