That's good advice from
@#blackpowderbill
It's a lot of work to sell them yourself. If there is a reputable used book dealer in your area they would probably love to take them off your hands for a fair price. You won't get as much as you would if you did it yourself, but you would save yourself a big headache. Personally, I would stay away from any business associated with Amazon like Abebooks, or Half Price Books or Powell's. They typically offer pennies on the dollar. A small mom and pop book shop will give you a better deal.
If you want to make the most off the sales, however, just make a list with titles, authors and prices, and post it in the "for sale" forum. If you include postage in your price (just add $5 to $10) it makes it a lot easier than having to calculate later on.
Hope this helps.