Since you are caving, you will probably have a headlamp with you anyway, but it is worth repeating that there is nothing more handy than a good headlamp when camping. The Tikka Plus is my favorite.
When sleeping on the ground, or even on a cot, a Therm-a-rest air mattress will aid your comfort tremendously.
Having an actual tick removal tool (not tweesers) is a good precaution. There is no safe, effective way to remove a tick without one and you usually can't buy one quickly when you need it.
Take some anti-itch cream such as cortizone to tame any bug bites you will definitely get. Your companions will love you for this.
Foam ear plugs will help you sleep when the people around you are snoring or otherwise making noise.
Take some entertainment such as a frisbee, guitar, marshmallows, book, etc.
And finally, a carefree attitude and some fun people to share the experience with will guarantee a good time.