eBay's search system has seen a lot of change over the years, always the subject of seller complaints (thanks to things like best match rankings) and buyer confusion (particularly about power search techniques), but at the end of the day, eBay searching remains the very core of the eBay experience.
Happily, you don't have to become a search expert or an eBay developer in order to make eBay search work for you most of the time. You just have to remember a few basic dos and don'ts:
Don't include article words in your search
Since eBay's search system normally displays only results that match all of your search terms, searching for "The Jetsons" or "The Beatles" returns far fewer results than just searching for "Jetsons" or "Beatles" does. The same goes for "Movie A Beautiful Mind" versus just "Movie Beautiful Mind" when searching for media titles.
Don't include too many search terms
Because eBay's search tool defaults to requiring all of your search times for an item to appear in results, typing "unlocked iPhone excellent condition with accessories" will only show you listings that have every single one of those words in the title—and may hide from you hundreds of listings for unlocked iPhones in excellent condition with accessories that don't include all of these words in the title. Stick to the basics ("unlocked iPhone") and browse through the remaining search results, perhaps applying search filters (see below) to find what you're looking for.
Don't use keywords for item conditions
Unless you're searching for something very specific (like "Mint In Box" or "MIB" condition) using jargon still seen at times in specialized eBay trading circles, searching for item conditions ("working clock" or "new sony laptop") will tend to hide many desired items from you, since the item will only appear in your search if the seller included the same word you're searching for.
Do narrow your search using the filters on the left side of the search results page
If you're specifically looking for a used item, a new item, an auction, a Buy It Now listing, an item for which returns are expected, a nearby item, or any number of other "specifics," use the filters on the left side of the search results page to help you find those items after you do your initial keyword search.
Don't automatically buy the first item in search results
There's no point to having a search system as complex as eBay's, or to using a site like eBay (rather than something much simpler like Amazon.com) if you're prepared to buy the first item in search results. Instead, try sorting your search results in other ways to see whether you might be able to find a better deal.
Do search for Buy It Now and sort for lowest price
The top results shown for a search are often not the best deals available to you; you'll often see better prices on immediately available items from sellers with equally good feedback and ratings by clicking the "Buy It Now" tab over search results, then use the "Sort by:" drop-down list to select "Price + Shipping: lowest first."
Do search for auctions and sort for soonest endings
Another way to find great deals is to search only through auctions that are just about to end, meaning that they've almost reached the price at which they'll sell, barring a flurry of last-moment bidding combined with a high proxy bid or a sniping attempt. To see these, click the "Auctions only" tab over search results, then use the "Sort by:" drop-down list to select "Time: ending soonest."
Do use the alternate search results views
By default, you'll get eBay search results as a list of items and titles, but that's not the only way to browse eBay. Just under the tabs along the tops of your search results, you'll see the text "View as:" and a series of three icons. The second icon is the gallery view, which shows your results as a grid of pictures. The third is the side-by-side view, which shows you a column of Buy It Now results and a column of auction results and lets you sort each column independently—say, by lowest price in the Buy It Now column and by soonest ending time in the auction column!
Don't limit yourself to eBay's search system alone
eBay's web-based search is powerful but offers only one take on eBay's huge database of items. eBay's mobile app search is even more limited, often basically limiting you to best match results. Consider branching out to search eBay using Google (visit shopping.google.com and enter your keywords followed by the text "site:ebay.com" to search only for products on eBay) or for alternate search tools like Typo Bay, which can help you to find hidden deals, Get It Next, which limits the appearance of accessories and other "secondary items" in search results, or SeeIt.com, an innovative search tool to help you find jewelry on eBay visually through "similars," rather than using words. Find other "alternative" eBay searches by searching Google for things like "better eBay search."