We just did a sale and earned $375 for about 15 hours of work, 8 being the actual day of the sale (set up, take down) and the rest in prep, such as washing, folding clothes, cleaning toys, dusting furniture pieces, sorting and shelving books, making signs, pricing and placing ads and signs.
This took the work of two adults. Our kids are old enough to "help", kind of, but really they still needed one adult's full attention to keep them safe/entertained during the sale day, which was 98 degrees and way too sunny!
We made very little of the money on clothes, and we had marked all the kids clothes at 50 cents, then reduced it to 25 cents half-way through. No one was buying kids or my adult clothing this year, even though we had some really cute stuff like Hanna Andersson, Gap and hand-knit items. We priced kids books at 50 cents for soft cover, $1.00 for nice hardcovers, but still had about 20-30 left.
I think if you only have clothing, shoes and some toys you could state that clearly in the ads you place in your local paper and Craigs List, so the people that come will come for those items. But, unfortunately, aside from the toys, the other items don't really sell too well at garage sales in my experience. Or at least not for the price you would hope.
Perhaps a "lot" offering on Ebay, like "Lot of 5 size-4 girls summer dresses"? I don't sell on Ebay or Craigs List, but I know some other ladies here do and could coach you through it.
Another option is to make an appointment at a kids thrift store or consignment shop (Oh Joy! is located in Oak Park) but I have not tried that either. With consignment, you only get paid when the items sell, then you have to go collect the check. Places like Once Upon a Child or Thrifty Baby, which are second hand stores, give you $ right then, I believe, but I have heard that they are picky with what they take and the reimbursement is not too high.
We donated what remained of our garage sale stock on www.Freecycle.org. You just register and then people send you replies to your posting of "Bag of girls' clothing" or "box of girls toys" and you pick who gets them.
Good luck!