How to apply “nocache” in wordpress?

Hi folks — I’m trying to keep various search bots from caching my content — on the blog and elsewhere on my site. I don’t care if they include links to content on my site in search results; I just don’t want them essentially hosting my content with cached material. I’ve learned there are broad measures I can take in a robots.txt file or I can use meta tags in the header of html pages. Maybe I’ve used them incorrectly, but they don’t seem to apply to my blog, which is in a directory inside my main site. Anyone know how and where to give bots some limitations as they crawl a WordPress blog? Thanks in advance.