I was shocked that you didn't get more advice on this since these sales are so popular. I am not sure how St Ephraims will run their sale but I have done the Snugglebugs sale in Pittsburgh that someone else made reference to.
I will say that newborn - 24 month clothes can be a tough sale. There is such a volume of those clothes out there and the babies grow out of them so fast that they typically do not look worn or stained.
If you have anything that needs ironed - iron it! I personally do not want to buy anything I will have to iron so if you make it look like it is wash and wear...well your chances of selling it are better :-)
Toys and baby gear typically fly out the doors of these sales.
If you have to put everything on a hanger make sure it is on the correct size hanger. If it falls to the floor than noone will pick it up let alone buy it.
Typically you want to hang everything on the hangers in the same direction.
Some sales claim that outfits sell better so to group items. I am not completely sold on this idea unless it is a Gymboree outfit etc. Of course it could all be in how the items are displayed at the sale. I know at the SB sale, the outfits are hung on a lower rack and I gravitate towards the upper rack with the separates...maybe it's just me.
Don't mismatch sizes. It irritates me when I see a size 18 month bottom with a 3T top.
I don't believe you are near Pittsburgh but the Snugglebugs website does provide some good guidelines for presentation etc. It might be worth a peek especially since you didn't get a lot of responses.