I've recently done this - for the second time.
My method is easy: give away absolutely as much as possible; firstly to
family and friends, and second as "FREETAGH" (free to a good home) listings. Basically, I only
endeavour to sell items which are simply too valuable to give away. Generally, this is items which might fetch a
sale price of $500 or more. Some lower value items may get
sold, if I know for certain they will sell quickly, and with a bare minimum of effort on my part.
Unfortunately, when selling used items on the flea markets that are CL, Kijiji, and other online classifieds, you will experience a feeding frenzy of time-sucking inquiries about your listings, with few actually intending to
purchase. You will avoid most of this by listing items for free, though still be prepared to witness the unspeakable sense of entitlement extant among your local neighbours. (Being told I was unfair and SELFISH for declining to deliver an item I had listed for free didn't sit well with me, elaborate sob story about the other party's circumstances notwithstanding.)
Once you've given away most and
sold the rest, you will feel much rewarded, and hopefully minimize the amount of stuff that ends up in the trash.