Mayumi WordPress theme comes with 5 color schemes to choose from. All the features can be accessed via the General Settings, Social Networking Settings and Custom Advertisement Settings tabs from the Admin Panel.

Activate the Required Plugins
FlickrRSS
Popularity Contest
TweetMeme Retweet Button (note on the settings, see below)
WP-PageNavi
Yet Another Related Posts Plugin
Customizing Mayumi Options:
Go to Appearance > Mayumi Options
General Settings
Social Networking Settings
Custom Ads Settings
Then Save Settings.