I would say signs are the best way to go. Make them clear and legible though!! I don't know how many signs I see each weekend that I can't even tell what's going on or where to go! Go out to major intersections to put them up and lead people into your neighborhood with signs along the way. You can make some that just say Garage Sale and your street name, then as they get closer they can have more info if you'd like. We used to use bright colored poster board. But while the neon colors get people's attention, they are sometimes hard to read what's been written on them. So just make sure that your letters are big enough to be clearly read. Big, bold arrows also help.
You might include on some of the signs something special about your sale, too... like if you have furniture or baby items, etc. those simple indicators will help attract people as well.
Good luck!!
Oh, and check to make sure your city doesn't have an ordinance about g-sales. Some won't let you have one two weeks in a row. If they require a permit, the information might be on there. :)