Clothing

Traditional caving footwear is white rubber gumboots. Also other slip on gumboots, lace up gumboots (Ashleys). Tramping boots, sneakers, etc.
Considerations are the protection of your feet, keeping the dirt and gravel out of the boots, and ease of getting them on and off.
Boots must not have hooks if you're going to be using a ladder. Waterproofness is not a consideration.

Heavy duty long wristed rubber gloves.
Also have seen kitchen gloves (not recommended), gardening gloves, polypro gloves (not recommended). NZ Safety or Hardware store

Neoprene with two velcro straps, above and below knee. Worn under overalls to stop mud clogging velcro. (Eazi-fit Knee Protectors product number 971478 velcro fastening neoprene pad suitable for wearing under overalls) Also have seen roller blade knee pads (bulky and rigid) (not recommended), other kneepads (more expensive, poor fastening, or loop fastening).

Equipment

Attached to caving helmets, or elasticised for tramping or climbing use. Any headlamp can be taped, cable tied (recommended), or otherwise attached to a helmet.
A few beginners options: Nitecore HC60 Cree XM - L2 U2 1000LM LED Headlamp w/ Intelligent Charging Circuit, Fenix headlamps

Accessories

The following are useful accessories.

Small, Aspiring Enterprises

Standard, Aspiring Enterprises

Small, Access Gear

Large, Access Gear

Polypropylene recommended. Macpac do a great range of underwear and crop tops. Earth Sea Sky and others do fine balaclavas, singlets, long johns, and skivvys. Considerations are warmth when wet, no absorption of water, and ease of drying.

Miscellaneous

35 litres

6mm