The key to this is variety as you wouldn't want people to have hundreds of the same thing!
Step2
Make sure that any items you are unsure of selling then don't sell!! You don't want to sell things that you may want back later on as you wont be able to get them back later on!
Step3
Apart from that anythings for sale so just keep packing!
Step4
Don't overprice!!-This is absolutely key as people wont want to pay for second-hand stuff like they would pay in the shops to get it first-hand
Step5
Set up your stall and sell stuff.Make sure you make your stall look attractive and you could organise it in a specific way to highlight the bits you would really like to sell.Happy selling!!