I remember when my older son went to an overnight camp for the first time I wasn't sure how to pack his clothes, he was wearing the same shorts on the last day of camp as on the first and all his clean and dirty clothes were mixed up in the bag. So next time I sent my kids to an overnight camp I was well-prepared:
1. I packed a set of clothes for each day in a ziplock bag - a t-shirt, shorts, an underwear and socks. Each day they had a fresh set of clothes.
2. 7 sets in total for one week of camp
3. I packed extra bags with pajamas and warm clothes
4. Extra large bags for sleeping bags and blankets. It is important to have all bags transparent so kids can see what is in there without digging through.
5. And I gave kids one empty extra large ziplock bag to collect laundry. Make sure kids can easily close it and open, to keep the smell in (good luck opening this bag when kids get home :))))