General tips
Pork shoulder under 18 h won't shred. The collagen needs at least that long at 160°F to fully break down - anything less gives you a tender roast you can slice but not pull. The 22-hour mark is the sweet spot for that perfect, fall-apart texture.
Dry-rub at least 12 h ahead. Pulled pork lives or dies on its bark, and the bark only forms with deep seasoning. A simple rub of salt, brown sugar, paprika, garlic powder, onion powder, and black pepper, applied liberally and given time to penetrate.
Save the bag liquid. After 22 h that liquid is concentrated pork essence and rendered fat - it's the most flavorful component in your kitchen. Strain it, defat it, and reduce by half for a finishing sauce that beats any bottled BBQ.
Mop with vinegar sauce after pulling, not before. Carolina-style vinegar sauce (apple cider vinegar, red pepper flakes, brown sugar, salt) is mixed in after the meat is shredded so it gets distributed evenly without being cooked into bitterness during the long bath.
Anti-tip: don't let the bag liquid go down the drain. I'm saying it twice because everyone does this. That liquid is gold - use it, don't lose it. Even if you don't have an immediate use, freeze it for next week's beans, soup, or rice.
Fall-Apart Tender tips
Pork shoulder (Boston butt) is the traditional cut
Remove bone if present, or cut roast to fit bag
Finish with smoke or grill for authentic bark