sell your familiar and interesting goods
you can sell all of the goods that someone else says saleable!because maybe they sell well but when more and more people get in,it must get vicious competition,then you can still sell them well ?of course,there's some goods that will never out of season,so you can get your customer by its good quality,timely customer service,find out them.
or you can sell what you're familiar and interested in,which will save you much time,maybe it will go on well.