As a fairly experienced sales person i have noticed ways to get your old items that sit for a while, if at least a higher interest, and a possible sale
To mave out and makeway for new items.
Displaying your items nicely, uniquely, and desireablly is extremely important.
If u are a regular on garage sale, flea market circuit..many of the buyers very well may be too
So u always want to keep new and different stock in rotation, aside from your 'best selling' and 'not selling merchendise' even if they are nick nacks make sure what you put around your items draw attention or serve a purpose. If you can draw them in, u can usually talk them into taking a package deal of the item of interest and the flat stock items.
Show some creativity, make your display appealing to the eye. Walkers by are so overwhelmed with eyes gasms at these types of events, something beautiful will focus attention.