When preparing the blogs for large amount of traffic, first thing I usually do is install a caching solution for WordPress in form of WP Super Cache plugin by Donncha O Caoimh.

From the plugin page:

WP Super Cache is a static caching plugin for WordPress. It generates html files that are served directly by Apache without processing comparatively heavy PHP scripts. By using this plugin you will speed up your WordPress blog significantly.

WP Super Cache has simple settings, and is reasonably easy to install. However there is one option that needs to be treated with care.

If you experience slowdowns on your blog page even after turning WP Super Cache on (and occasionally even get garbled output on your pages) you need to disable Super Cache Compression.

This will turn off compression of the pages which will save great amount of CPU time, especially on shared hosting servers, while still retaining the caching abilities of WP Super Cache.

After this your pages should fly.

Courtesy Vladmiri