10. Lard/Grease: Whether a squeaky door, a greased staircase before a fight, or assisting with opening rusty and old latches, having some lard and grease is always useful.
9. Tiny birds: A lot of times, you'd like to see what would happen if someone went somewhere, only you don't trust it enough to go. With this small sack of birds, you can check for traps, trade to people for passage, notice if the air is toxic, or even distract unintelligent opponents. Taking them along extends your life, at the expense of theirs.
8. Paying attention: At its core, Dungeons & Dragons is about exploring a resonant fantasy realm filled with archetypal representations. This process is handled by conversation using the Socratic method. You ask questions, the Dungeon Master gives answers, yeah? If you're not asking questions or listening, you're watching your friends play Dungeons and Dragons. When you all jump in and work together, it raises the experience for all involved.
7. Gloves & Helmet: If you don't have to touch something with your bare hands, don't. Don't press parts of your body (like ears or eyes) against things. You call people that don't wear covers corpses. Get a hat, preferably one made out of metal that lets you see in the dark, grants telepathy, or makes you smart or something. There very well might be treasure in the garbage or latrine, there almost certainly is, but you don't want to go in there yourself.
6. Equipment shenanigans. Casting a light spell on a shield lets you see opponents and plays havoc with enemy archers. Buy a metal sectioned pole, so you can attach a hook, vary length, and carry one in cramped quarters. Collect potions and scrolls and don't hesitate to use them, there's always more magic to find.
5. Hammer & Piton: It holds doors both closed AND open. It draws a lot of attention. It allows you to attach rope to things. They solve problems.
4. Torchbearers & Porters: Yes it's difficult to convince them to head into dangerous territories, but when there are a lot of things that need to be done, having a man or two around who can do them is helpful. Purchase them brightly colored festive outfits. Give them nets and poles to trip up enemies, ball bearings, oil, caltrops and other things they can throw. They can pull people to safety and best of all, they draw archer fire. People don't get into this vocation because they want a safe workplace.
3. Elves & Dwarves: Everyone loves their half-demon, half-cat, half-turtle, kenku-whatever sub race, but facts remain. You want an elf for secret door detection and a dwarf for detecting stonework traps and sliding doors. Often they can see in the dark. If you don't have one in your party, hire one in town as a buddy.
2. Oil: You don't want to need it and not have it. If you want to be sure something is dead, burn it to ash.
1. Ten-Foot Pole: You will want to touch things and not be near them. Trust me.
I hope you explore some fun dungeons this weekend!