
First is the bottom layer. You will want to pack flat reference materials such as maps, important documents and survival manuals along the back wall of the main compartment. Keep all documents and maps in plastic bags to protect them.
Next is your middle layer of the main compartment. You will need to add the items that you will probably only use at the end of the day. These will be things such as a fire starting kit, emergency blanket, toiletries, possibly a tent and so on.
Now the third layer of the main compartment is the top layer. this is where you should have your bulkier items like your poncho, socks and underwear, tarps and emergency radio. Put these on this layer so that you can reach them without having to unpack the whole bag.
The next step is to pack the top exterior compartment for compact items you'll want available throughout the day. Basically used for snacks, a knife, and other small essentials.
The left side pockets should be long so that you can fit a hydration bladder, unless the bag has a spot built in for one. Keep your portable water filter in this pocket as well.
The right side pockets can be to hold long, slender tools such as your fixed blade knife and flashlight. Those things can easily get lost in your main compartment.
Now, for bulkier items, you can always strap them to the outside of your bag if you run out of space in the main compartment. These items would include a sleeping bag, first aid kit and extra water containers.
Consider purchasing accessory straps, and make sure that you take a couple of garbage bags and extra Ziploc's in your backpack. They are essential!

