I second the Trail4r website. Essential? I don't think much would be qualified as essential in my book. I'd bet most guys here have gone out with little to no gear when they were new. If you have a capable vehicle and a friend with some experience, you should be alright if you stick to the mellow trails. Rant over, if you want some cheap stuff to get you on trail, I would recommend at least:
A decent tire gauge, ARB or the like
A small tool set, Craftsman/etc. with wrenches and sockets
A shovel, I have this one
https://www.amazon.com/Bond-LH015-Mi.../dp/B000X47NJY
A tow strap, bought a cheap one from 4WP 9 years ago and it hasn't failed me yet.
Also, I would agree with
@
mscot
on the wood, great to throw under the factory bottle jack in a pinch.
Other than that, take it slow, keep your eyes open and have fun.