Ever wondered what order the episodes of Doctor Who (2005-) should be watched in?
If you watch them in order, you're missing chunks of the story.
Consider interspersing your viewing with episodes of Torchwood and (if you can find it) The Sarah Jane Adventures. Some of these episodes bleed into one another.
Check out my spreadsheet to see if you should watch "Last of the Time Lords" before you catch Torchwood Season 2. (Protip: yes, yes you should.)