I am by no means a winemaking expert. I wouldn't even say I was at an intermediate level - more an enthusiastic and curious beginner with three years' experience. Along the way I've picked up a few nuggets of knowledge that may help the aspiring young vigneron out. They're numbered in no particular order.
1. There is nothing cuddly in a winery. The tanks are steel, oak, epoxy or concrete. The hoses are reinforced and have stainless steel at each end. The bottles are glass. The pallets splinter. Pretty much everything is heavy or sharp or hard. Some things are all of those. Be careful.
2. If you forget rule one and do hurt yourself, don't bitch. Don't stop if you're in the middle of something. Everyone's hurt themselves. Everyone is bleeding or just scabbed over, with bruises forming and bumps rising. Anything short of a broken bone, lost limb or death can wait. Just try not to bleed into the wine and when there's a pause, find a bandaid.
3. Making wine hungover is something you only need to do once to learn it is the worst fucking thing in the world. Remember: self-inflicted wounds deserve and receive no sympathy.
4. Drink a lot of water.
5. You don't have to be a morning person, but you have to function in the morning, regardless of how miserable and grumpy you are. Everyone around you wanted an extra hour or two in bed and none of them got it.
6. There is no 'are we there yet?' attitude, there is only 'what can I do next?' attitude.
7. If there's coffee, drink it. You'll need it.
8. If there's wine at lunch (and there will be in France), take it easy and match it with water.
9. Try, if you can, to get a bit of breakfast.
10. If someone else is lazy, it's not your job to call them out. Their laziness will reveal itself. Focus on what you're doing.
11. Always double-check the valves. Wasting wine is a terrible, terrible thing.
12. Do your job and be helpful.
13. Learning what not to do is every bit as important as learning what to do.
14. When in doubt, ask. It's better to be annoying than to do something wrong.
15. Nobody likes a smart ass. That's applicable well beyond winemaking.
16. Don't stick your hand in the de-stemmer.
17. Make sure you know where the emergency stop button is on every bit of equipment you use. It's usually big and red.
18. Make sure everything is clean at the end of the day. If you half-ass whatever you're cleaning, you can fuck it up for everyone.
19. Don't fuck it up for everyone.
20. Have fun.