I haven't hurt myself modeling yet, other than utterly destroying my faith in my own abilities and multiple hits on the wallet.
I work in printing and used to to pasteup and layout using a #11 Exacto, and you learn very quickly not to try to catch falling knives and to tape a "flag" or a piece of sprue on the handle end with masking tape to prevent it from rolling. Also teach yourself to put the knife down at right angles to you. That way if it does roll off the table, it's not towards you. Level tables help, too!
I've also learned to keep my work area free from paint pots and bottles of glue, unless I'm actively working on them. I use a piece of 1/2" plywood with holes cut through to hold the ones I am working with.
So far the worst mistake I've made is when I used a color cup on my AB for the first time and tilted it enough to dump most of the contents out on my newly finished and freshly painted spray booth. The booth is bright white, and the spilled paint was (of course!) black. A constant reminder of why you should be aware of the color cup!