1- plenty of food and water - even more than you think you need, actually. You’ll thank us for this when plans change and you’re out longer than expected.
2- navigation tools - compass, map, etc. Don’t rely on your phone, if it dies/doesn’t have enough service to do what you need, you’ll want a back up.
3- first aid kit - something that includes foot care and bug spray.
4- knife - knives can help you get out of sticky situations in the wilderness including self defense, we suggest a bowie style knife but a swiss army knife could always come in handy.
5- ox mat (for shelter and sun protection) - your ox mat can be used as a barrier between you and the ground, or you can hang it up to protect you from the sun/rain. Can also be used to carry any of your hiking buddies who are potentially injured/sick.