Vintage postcards are perennial best sellers, on and off eBay, and you can make double or even triple figure sums from a postcard that cost next to nothing or which you obtained free of charge. These tips will help make sure you profit big time:

* Oftentimes a topographical postcard has some other feature, such as a postmark, postage stamp or autograph that makes it more valuable and likely to interest more than just postcard collectors.

* Real photographic postcards were created individually and required constant attention during the development process, unlike most printed postcards that emerged from machines in their thousands and were often poor quality compared to real photographs. So a good real photograph of an unusual event could be very rare, possibly unique, and fetch hundreds of pounds if just two people are desperate to have it.

* Generally speaking, the older the card, the more valuable it might be, although some modern cards are valuable for other reasons, because they are autographed, for example, or belonged to a famous owner.

* Avoid unnamed locations except for really unusual cards or where clues exist to their location which you can check and verify and add to your eBay listing. A postmark, for example, or a sender's address, might feature the location of the topographical view.

* Keep listings separate for postcards from the same or nearby geographical areas. This is because some people will be making last minutes bids on several items which, if selling too closely together, could find them missing some auctions and become disappointed and harassed and even losing interest altogether. Five minutes between listings is enough time for people interested in consecutive items to move between bidding on one card to bidding on the next.