One of the first things I do before launching a wordpress blog is to activate Akismet plugin.(Which is already a default plugin when you install wordpress)
What is Akismet?
Automattic Kismet (Akismet for short) is a collaborative effort to make comment and trackback spam a non-issue and restore innocence to blogging, so you never have to worry about spam again.
How to Activate Akismet Plugin?
1. In the wordpress admin, go to Plugins, then click Activate, to activate Akismet Plugin for wordpress.
2. A message now appears in the header to enter your Akismet API Key
Question: Where do you get your Akismet API key? You can get it here for Free
3. Now you have your Akismet API key, enter your Akismet API key. This message should appear.
Note: You can use this Akismet API key in an unlimited no. of personal blogs.
Although some spam comments may still appear, at least you can already lessen the spam comments with Akismet.