Talk to the boater, stress to them that you don't want to be a bummer for them. I do that because every guy is different. Some don't mind if you bring 10 rods and a ruck sack full of tackle, others aren't psyched if you bring a single rod and 3 senkos. In time you'll figure out what you need to bring and not bring.
There's a guy in our club (AOY or 2nd each of the last 4 years) that uses 2 spinning rods both rigged with the same bait. He switches the weight on occasion and rarely the color, but that's all this guy brings and uses and he stomps us regularly. This is to say that you should bring what you know you can catch fish on and no more. You don't need all 12 colors of senkos that you have in your bag at home. I used to get all spazzed out looking at all I brought and just confused myself when it came time to change baits, wasting time and losing confidence (have confidence is the real deal!)
Generally the non-boater gets one of the compartments in the back of the boat, I always plan on that compartment being the size of a Nitro Z6's (small). This way all my stuff isn't wedged in there and taking me a ton of time to get too and making a big mess on the boat. Likewise you will often be kneeling where the livewell hatch is and you'll not want to be in front/on that for too long if the guy wants to get in there. Again it's all about not being a neusense, if you're cool to them they will be cool with you and that makes the days much better.
Keep thier boat clean, unhook bleeders over the side of the boat, don't let a pickrel in the boat (we're weird about that up here).
Ask what they do about netting. Do they call out something and want you immediately? Do they never use a net? Only the big ones?
Take care of thier fish first if you get doubles.
MY Suggestions: (I live on Champlain big lake with lots of variety)
"Big Rod" C-Rigs, flipping, frogs (766 Recon/CuradoE/50lb braid)
"Common Rod" Swimbaits, spinnerbaits, footballs, some flipping, some flukes, rarely bigger cranks/jerks (715 Recon/CuradoE/16lb Fluoro)
"Pixie Stick" Spinning rod for Fat Ika's/Drop Shot/Senkos/Shaky Heads/smaller cranks and jerkbaits (Lamiglas Excel 703/Pflueger Supreme XT/20lb braid)
"Trebles" Jerkbaits/Cranks/Topwater (6' 6" M Daiwa Tierra/CiticaE/30lb braid w/leader)
"Just in case" I use for spinnerbaits, swimbaits, spooks, buzzbaits, if I already have a bait I am using on the Recon or Tierra, I'll use this one for another I'd use them for (6'10" MHxf Compre/CiticaE/ 12lb Yo Zuri Hybrid).
MAX 6 3600 sized boxes, occasionally a small worm wrap as well.
Scale, Culling Clips, lunch. pliars, something for leaders (C-Rig/DS), glasses, rag.
Offer to pay thier entry fee or gas (our club tourneys are $30 so they are cool with me paying for them and call it good.)
I offer to share if I am on fire with a certain bait, but try not to be annoying/obnoxious about it.