I don't have any great steel heading stories/lessons to share as I am relatively new (5ish years) to this pursuit. But I will advise on one thing to bring along that I learned the hard way - toilet paper!
Went out one morning a couple years back. No brown trout before I left home. I figured no big deal, if I have to go I'll just wrap things up at the run I'm on and hit a gas station. Around lunch time I was fishing a run above Tamahai, about a 15 min walk from my vehicle. Suddenly it hit me - anal urgency! I tried to make it back to my truck but I knew it was not going to happen. Next thing you know my clothes are coming off faster than an X rated movie, trying to get my damn waders down! I had no t/p, and the only thing "usable" around were some giant, wet, gritty, muddy leaves
I did the best job I could and had to fish the rest of the day with a gritty/muddy butt crack. Not nice!
Now in the same big zip lock I keep a few garbage bags and smaller zip lock roe bags, I have a small pack of "wet ones" along with a small roll of t/p. If you have to take a beef dip in the woods you'll be glad you brought this stuff!!