Haversack / rucksack - Durable, tough and lightweight - OK to spend a bit extra, in the long run I can ensure that you won’t regret. One 35-40 liters, plus another smaller one (about 10-15 liters capacity) for day trip.
Shoes – Can be a trekking or any ordinary sports shoes. Make sure you get a pair that can take a lot of abuse because that’s what's going to happen especially when you decent the mountain. My favorite is the "cheap" rubber shoes used by rubber tappers ! Very lightweight, suitable, and most of all comfortable, especially in our Malaysian jungle.
Wardrobe – Get warm clothing that is wind and rain proof, easy to put on and take off and not too bulky or heavy. Warm clothing may be too warm at lower altitude so, get extra rain coat. The weather can vary from sunny to mist to rain and wind within minutes as you move through different parts of the forest and altitude.
Warm clothing, long sleeve shirts / T-shirts, wind breaker, rain coat/ jacket. Lightweight cargo pants, ¾ length sport pants, boxer shorts / underwear, sarong (my favorite item – don’t leave home without them !) Lightweight towel, bandanna, snow cap, baseball cap, gloves.
Gloves – You need one that can take abuse, something that you don't mind getting bruised. When you are all so tired and still have to decent the summit, you will most likely grab onto the ropes and run down the slopes and grabbing the ropes to slow down yourself. It is actually easier to run/walk without break than to walk down the mountain.
Mask – You need one that can hide your entire face, like the ones robbers use unless you don't mind the wind "biting" at your face.
Food – Just bring some high-energy food stuff like chocolate, nuts, raisins, glucose sweets, biscuits etc.
Torch Light – Or a headlight, more practical as your hand can be free. Bring one that is ultra bright and ultra light if you can. I promise you won't regret it. I still remember those days when I used to drag along a 3 D-cells torch light weighing at least a couple of kilos. Now that I am older & wiser, I carry one that takes only two AA batteries. Not as bright as I would like but it does the job.
Medicine – Headache tablets are the most useful. You can take them before climbing and after heavy rain or when you get headache. Diarrhea and vomit prevention tablets are useful too. Please take into consideration that you will experience variations in atmospheric pressure and unpredictable weather. People with high blood pressure and other health problems are advised not to climb but no one is going to stop you from climbing just be careful and know when to quit. Pack up also deep heat lotion, minyak gamat, plasters & insect repellent.
Tent & Sleeping Bags – If you plan for an overnight camping, bring along a small lightweight tent (for 2 ?) and a sleeping bag. I prefer sleeping in the hammock under a flysheet. Bring also durable ropes and some nylon (parachute) strings of abt 3-4 m long.
Miscellaneous – I always bring along second pair of dry cloths, socks, disposable poncho, plastic bags (to put all your things in, unless your bag is rain/water proof), toiletries etc. Mobile phone & digital camera (don’t forget to bring extra batteries). Binoculars & whistle can come handy at times.
Super tip – Travel light ^_^