I ran a garage sale with more of a mind of getting rid of stuff in advance of moving than making serious coin. My mother, a garage sale queen, gave great advice: create a 25-cent table and a dollar table. People destroyed those. I held firm on a few things like an old Callaway driver and a signed Billy Donovan Gators basketball (got $10 for that, three years ago, now I wish I had it back), but mostly it was a true junk sale. I made a little over $200, mostly quarters and dollars at a time.
And yes, the earlybirds were amazing. I couldn't unload my boxes fast enough, so they just helped themselves. I wasn't offended in the least.