My girl friend and I go to tag/yard sales all the time. We've also hosted a few.
A few suggestions...
Advertise - You may want to take out an ad in your local paper. Make lots of signs. Be sure you can read the date. It's hard to read an address so sometimes a simple "Yard Sale - Sat 8/3 - 1/2 mile ---->" is best (depends on your location).
Pricing - It's a balance of how bad do you want to just get rid of it and how much money do you want to make.
For those really nice outfits, jackets or snowsuits that are good quality (oshkosh, healthtex, gap) and still in good shape, you may want to price them individually ($2 to $5) and lay them out on a table or hang them.
For all others consider $.50 per item, 2 piece $1.00, 3 piece $1.50. Keep it simple.
I usually won't take time to sort thru a bin/box. If you use bins/boxes clearly mark it's contents, example: sweatshirts sizes 3 to 7.
Have lots of change available. One of your first customers will spend $1.50 and give you a $20.
Toys usually sell really well. Make sure they're clean and have all the parts.
Ask a friend to help.
Check with some neighbors and see if they might be interested in having a yard sale at the same time. Neighborhood sales usually attract more customers and you can split the cost of an ad.
Be prepared to bargin. I've had people show up at my yard sale expecting me to basically give the item to them (I'd price it for $4, they'd offer a $1)