Posted By:
Steve MurrayTo quote someone else on the board, "if we told you, we'd have to kill you". 
Searching is not an exact science. Most will already have catagories bookmarked that they will peruse each day for new listings. Many will use words, such as "Obak" and search all catagories. Some will search mispellings
e.g. Matthewson for Mathewson. Some will search "old baseball card" or "old picture of a baseball player" to see what they can get.
As for T206 or T-206 I think the ebay search function is not so discriminating as to exclude one when the other has been requested. Though Zeenut and Zee-Nut will often come up with different results. To be safe I would search both. There are some major auction sites where you put in T206 and get nothing only to find there are 50 listings under T-206. 
Remember that your search is for what a seller has in his listing. Some are thorough, some are scanty. For that reason there really may be no "catch phrase" that would produce the results you want.