If it's just for a night or two, you won't need as much food or clothing as you would if you were going on a month-long epic.

Your second challenge is to make sure you have the right equipment for the conditions you will face. If it's going to be cold, bring warm gear. If it's going to be wet, bring a raincoat... you get the idea. Also make sure you have enough consumables. It wouldn't be a good idea to run out of gas for your stove or batteries for your headlamp. But be reasonable! The more you have, the heavier your bag will be. Think twice about whether you really need that extra thing or not.

Knowing how to fill your backpack

With a little experience you won't think twice about where this or that thing is going, or how to make your life easier, but when you start, it can be like a Chinese puzzle. Your bag has been designed to carry a lot of weight, but how you fill it will make a difference in comfort. Keep the heaviest things in the middle of your back and the lightest, and other compressible things lower or on top.

When you pack your bag, keep it long and thin so that the weight is distributed in the right place on your body. The compression straps on your bag will help you avoid ending up with a short, bulging bag.

Don't forget to keep your balance between the two sides of the pack equally - a pack that tilts to one side can be uncomfortable for your spine and shoulders. Make sure you keep as many things as possible inside the bag; a junk of stuff that hangs down, tied on all sides, will wreak havoc on your balance, especially if they're free to swing. Finally, the top flap pocket often becomes the "glove compartment" for multiple small items that ultimately create significant weight, so the top end of the bag becomes far too heavy - be careful!

Easy access to your belongings

Easy access to these cases for quick disposition. It is very unpleasant to empty your bag completely under a sudden torrential rain because your waterproof jacket was right in the middle!

Once everything is fully loaded and you feel comfortable, do a test while strolling around with your bag on your back. Go up and down the stairs to get into climbing condition. If you feel it's not perfect, you can still make all your changes to find the best solution.