I learned the hard way. Getting junk in your eyes is no minor inconvienence. For about 6 months I couldn't drive at night because high beam lights would make my eyes water so bad I couldn't see. Now I have a tiny blind spot. I discovered it by accident one night. When I look directly at a star it disappears. If I look a little right or left it comes back. That's the only way I notice it so It's no big deal. I'm lucky it isn't worse. If you're not as lucky as me your blind spot could be huge.

Another thing I learned the hard way is to wear rubber gloves when I'm doing bondo work. If you keep getting it on your fingers it will eat your fingerprints and dry your skin to the point where it will split and bleed. Don't try to hand sand like that. If you do get it on you wash it off as soon as you can. You can't get it off till it starts to kick (harden). It comes off easier with plain water. Soap makes it more difficult to remove.