The only engines that matter (for English content) are Google, Yahoo, and Bing - and soon enough, Bing's going to be powering Yahoo.
While you can get pretty technical about the ranking differences, practically speaking the on-page optimization process is the same.
Anecdotally, I've always found that Bing & Yahoo are easier to trick than Google...an exact match domain & some cheesy links will probably take you further in Bing than Google.
But, while backlink analysis / weighting / ranking is very sophisticated search engine stuff, on-page crawling of HTML is simple, and the basics of keyword labeling and logical architecture should cover you for any modern search engine.