Do not hold items unless people pay first. Masterson sells and buys as well, as most yard-sale fans do. People are trying to get rid of things. I love it. Masterson's plan to get good stuff involves driving the University and Nob Hill neighborhoods with a mixed amount of change for haggling.
Early birds arrive early just to get the good deals.
Besides getting out early, planning an easy route if you use the classifieds will maximize the number of sales you can hit. Bring a smattering of batteries to test potentially great electronic products. Plan to negotiate as a buyer. I'll ask questions like 'how much for the box of books,' and if they don't know then I'll make a ridiculous offer. Sometimes they say yes.