If you can, advertise in your local newspaper. They're always advertised in the Leader in our area. You can also advertise on egaragesales to get a bit more exposure. Put signs up on signposts in your area and put lots of balloons out the front of your house on the day to get more attention. Also, say "no early callers" in your ads so you don't get inundated at 6am with dealers LOL.

In your advertisements mention that you have lots of designer clothing.

With clothing - put prices everything, some people don't want to have to ask and sometimes you're so busy with other people that others waiting to ask you for prices just walk away. Don't price them too high if you want them to sell and maybe make a sign saying something like $5 per piece or $20 for 5 (or whatever price you're happy with).

HTH