Do Your Homework
It can be easy to look at a collection of stuff you no longer want and wonder who's going to buy it. But instead of treating your old stuff like a big pile of junk, look at it like undiscovered treasure. Take a little time to give everything a good cleaning. If you still have the original packaging for an item, put it all together. If you still have all your owner's manuals, tape them to the gear they came with. Do whatever you can do to make something look as appealing as it did when you purchased it. And, to be sure that you're bringing in top dollar for your treasures, take a look online to get an idea of how you should price everything.