bona fides: 10 yrs. as a paramedic and ER RN, then 20 yrs. as a physcian including some ER.

#1) appropriate training (don't need to be a doc, just trained). If you have to ask what size of suture, you probably need more training. (If you're planning ahead : 3-0 monofliament would probably be the best).

I carry a pack or 2 of 3-0 mono, but have never used it in 30 yrs. (safety blankie?)(yes. I rotate.), including some travel, days from standard medical care.