There are a few things that seem to be true for every auction seller when it comes to increasing their auction profits. Here are a few I've learned:
Selling in multiples: If you have an item that people are buying steadily (not necessarily the latest, greatest craze, but steady sales on something that everyone needs) it is more cost and time efficient to run multiple auctions using the same photos and descriptions, instead of having to write a new description for each and every item because no two are alike.
Selling similar products: Sell related products, and let buyers know that you have more of the item they're looking at in your other auctions. May be in different colors, sizes, maybe the items go together, like salon shampoo and conditioners, or maybe a blouse and the matching slacks.
Offer discounts for multiple purchases: If the buyer purchases more than one item, you could offer a discount. Buyers love discounts! I myself have bought multiple items from sellers just because I could get a second item with a dollar off, or a percentage off the total.
Offer combined shipping/handling charges: Another discount that buyers love is the combined shipping charge. This means that if they purchase more than one item from you, they can get all items shipped together in one package, and therefore the shipping amount would be cheaper. Some sellers offer combined shipping at actual shipping rate, and other sellers who charge handling fees as well offer reduced handling fees if the buyer has purchased more than one item.
Remember the seasons: Certain items I never sell at certain times of the year. Such as selling Christmas gifts and holiday clothing during March through September. I may be able to sell them, but they just won't get as much attention as they would if I waited until it is closer to the season, when people are willing to pay more for that item.