One of the decisions that a blogger needs to make is whether they are going to moderate (manually approve) comments or not. This decision should be made relatively early in the life of your blog.
For me, it is simply a question of what set of pros and cons you want to deal with.
Manual Approval of Comments
Pros: You can keep flames, slander, libel, and insults out of your comment section. Regular readers will also occasionally use a "Don't publish this, for this comment is for your eyes only" comment to privately communicate with you. You can also prevent publication of the most blatant advertising.
Cons: It takes time to moderate comments---the more readers you have, the more time it consumes. And some people will be impatient and claim that you have refused to publish their comments when in fact, you haven't even seen them yet. People will also be upset if you decide not to publish their trash talk.
Automatic Approval of Comments (with or without a verification of human intelligence)
Pros: You don't have to worry about making time to approve comments---in other words, you can post and forget. A hundred people can comment in an hour, and you do not have to do anything for their comments to appear on your blog.
Cons: You have to trust human nature. You will have to manually delete any comments that you wish would not have been posted, including insults, flames, libel, slanders, and advertising---unfortunately, other people will have seen these comments and spiders will have cached them. You will be accused of aiding and abetting flame wars. And sooner or later, you will end up with advertising you do not want in your comment section.
In my case, I chose to manually approve comments. There is one blog that I run that I might change my standard policy for, but it is not occult related (for the most part).