Depending on your skill level it can be camping season year round. These packing tips will not help you to survive the colds of the arctic or the jungles of Africa, but they will enlighten you. With some easy steps:

1) Multifunction Everything - you have limited space in your backpack, so everything needs to work all day and all night.

Pillowcase - The first big tip is to count your clothes, blanket and sack (blanket bag, not backpack) as one. The sack protects your blanket during the day, but at night can seem useless - but it is actually your pillow now. Stuff your used clothing into the sack and enjoy.

Towel/Blanket - This next tip is not for everyone - replace a summer blanket with a large towel. Some other campers argue that large towels take too long to dry, and that smaller towels are best for being exclusively towels. This isn't about the towel, it is about space. In the summer you could pack two large towels in the same space as the blanket and reduce the load. All the while making Douglas Adams jokes to other campers.

Glasses Cases - Glasses cases are good for keeping sensitive tools inside of, like toothpaste and soap. But I've used them for keeping batteries organized, holding usb/sd tools for photography, or even holding my sunglasses at night so
I can keep them from breaking. The inside isn't the only relevant place - by attaching 3M reflective tape to the outside you can use them as snap markers in a pinch. Another cool hack is adding a mirror finish tape to them for when you really need one.

GPS and Radio - Your car GPS may not be adequate. Your old iPhone cannot always find three towers to triangulate from. But you have a radio to call for help. Technology has seen more convergence than your blanket, and with it we can remove a couple more items from your pack. I had hoped that the Nokia N900 Computer would have included FRS/GMRS along with the satellite GPS, but for now offerings from Magellan and Garmin rank higher. Consider simple multi-mode devices, but don't break the bank trying to save 15 cubic centimeters.

Storing Mirrors - Like rope, a small mirror is the thing that people typically ask "Why?" and then which they had it once you are gone. The mirror is useful for signalling, inspecting bridges on trails, or for most vanity. Ok, ignoring the use of the mirror on yourself there are ways to bring it into your pack as a useful element. Use it as a rollboard for your rope, or attach one to a glasses case.

Rope Pegs or Rollboard - Never forget rope. It is always useful. How you pack it can change how frequently you use it. It is easy to loop and tie it to two or three hard pegs on the outside of your backpack to save space on the inside, but if you feel that keeping things inside the pack is important get a rollboard. Find a flat hard surface, nick a slot in it, wedge the rope and roll. This would be much better with a picture, but is very simple once you know it.

Those are the quick tips off th top of my head, hopefully they help you to pack lighter. Don't forget food.