I work as a model maker/prop maker/interactive fabricator and anywhere in between. The sort of things I do usually involve using a very sharp knife at some stage - often a utility/stanley knife or a surgical scalpel.
Right now I've got a few days off work, so I though I'd type up a few pointers that;ll hopefully prevent a few accidents
Rule 1: Replace the blade.
Blunt blades are dangerous. Not being sharp doesn't make them hurt less, it makes the hurt more. Also you're more likely to fuck things up if you have to force a blunt blade through material. Also:
Rule 1.1: Dispose of your old blade safely!
Blunt blades dangerous - don't just chuck them in the bin. A needle bin from the hospital, a glass coke bottle or a jam jar with a hole in the lid are all better places to put your blades. If you're caught away from home you should try and at least wrap you blades in a bit of duct tape before binning them, or take them home.
Rule 2: Plan your Cut
Put your pen and paper down - this is a half-second decision that is dictated by the shape of the thing you're cutting.
Rule 2.1: Cut away from yourself.
If you're right handed, hold you work with your left hand and cut towards the thin air on your right hand side.
Rule 2.2: Cut down onto something solid if you can.
I have holes in my trousers from not doing this. Get a self-healing cutting mat and use it!
(Always store your mat flat and horizontal. If you lean them against a wall for any amount of time they deform, usually pretty permanently)
Rule 3: Choose your knife.
Scalpels are good for light duty work, Utility/Stanley knives do better for bigger cuts in denser material. Snap-off type blades give you more width to work with. The thing is: blades are potentially brittle and when they snap you go out of control and things go wrong. Utility knives are built around the idea that you will be using a lit of force - stout handles, short, thick triangular blades. Scalpels are not.
Rule 4: Don't poke your fingers over the edge of the ruler!
I did this last week - nasty one in the side of my thumb. These usually heal quite quickly, but are still best avoided.
(While we're on rulers: If your ruler is going all wibbly-wobbly while you're cutting - try sticking it down with some masking tape. And cut along it rather than against it.)
Rule 5: Don't slice your thumb
Sometimes you will find the blade in contact with your skin. If you're fettling something really small for example. Try and avoid it (see Rule 2) but if you do, whatever you do DON'T SLICE. Just go straight back up the way you came. As soon as you move the blade in a sawing motion it will cut.
(Sometimes you have to do something a bit unsafe - just keep your wits about you, use a sharp blade and never apply too much pressure)
Rule 6: If you're not actually cutting anything PUT IT THE FUCK DOWN!
The majority of minor accidents happen when you never actually needed to be holding a knife in the first place. You make the first cut, move the piece for the second, check it with your ruler, and nick the end of your finger - it will always happen eventually. Make the first cut, put the blade down.
If you do knife yourself...
(Disclaimer - I know nothing about first aid)
Wash it out under the cold tap immediately. If you followed rule 1 it should be a nice clean cut - you probably didn't even feel it until the red water stared getting smudged about. If it's minor, quit complaining, get a plaster/bit of masking tape and be more careful next time. check it and clean it before you go to bed and maybe chew off any little flaps of skin. It'll be right as rain in a few days.
(I know guys who superglue their cuts. Nothing wrong with that... just don't spray it with Accelerator/Zip Kicker - that shit is exothermic, which means you'll end up with a nice burn inside your otherwise neat cut.)
If it's bad - DON'T PANIC. Talk to a first aider and get help ASAP. Keep pressure on the wound and elevate it - hold it up and keep holding it up until it someone tells you otherwise. Get to the hospital.
I mentioned at the start that I had a few day's off work, there's a reason for that. I violated rules 2 and 3 - fettling a notch in bit of 6mm ABS with a scalpel with it stood vertically on a table to around chin height. Cutting with my right hand towards my left using far too much pressure.
The only upside was I missed any tendons or important muscles, and, because I followed rule 1, it was a clean cut that allowed the surgeon to easily re-connect the nerve I sliced.
With something like a table-saw or a router, they both have noisy spinning blades - they are obviously dangerous, they demand respect. Where as knives, simple silent bits of metal are a part of our everyday life. It's easy to forget that they are potentially just as dangerous and need just as much respect.
Self harm is overrated - don't do it
(Thoughts welcome - If I've missed something or been confusing please tell )