1. I've only thrown one yard sale, and in my experience, it is a huge amount of work and prep (get lots of help if you can) for little return.
A lot depends on your location-is it busy enough to feed potential customers through, yet easy for drivers to pull over and stop? Do you have neighbors who will get upset at a lot of people parking in front of their home and possibly walking on their lawns? Are there big dogs around who can make a lot of noise even if safely restrained? Do you have room? Do you have the aforementioned help, to watch the inside of your house and to help set up and tear down? Do you have a charity that will pick up what's left?
2. It's good if you have a few really good things, or higher-ticket items to put in your ad or on your signs. The furniture might fit this bill, if it's in good shape. That's another thought: check ordinances in your city about posting "Yard Sale" signs on poles or trees. Make your signs visible, bright and legible and make sure they don't blow away before the sale. Sort the clothes by gender and size, and you might sort the books by fiction/nonfiction as well.
3. It can be either painful or a lot of fun, and if you have a good weather weekend for it, you just might do well. The object is to get rid of things, and so trying to make a little cash before donating all that stuff makes sense. Don't charge too much, but enough to move things, and consider going 1/2 price towards the end.
As for me, I'm personally skeptical of Freecycle, Craigslist and the other giveaway sites we talk about on this forum. All of those seem to have more pitfalls than throwing together a sale, never mind the risk of finding rudeness at best, a nut at worst.