1. Making it optional:
If you make it optional for students and parents to visit the classroom blog, they'll generally opt not to view it.
It is better to post once a week on the same day than it is to post three posts in one week and two the next and four the following week.
3. Lack of purpose:
I often hear people say, "I don't know what we should blog about." Without a defined purpose for a blog it is hard to come with ideas for individual blog posts. If you identify a purpose, "weekly reflections on learning" is a good purpose, you will find it easier to come up with topics for individual blog posts.
4. Running before walking or biting off more than we can chew:
Set realistic goals for your first semester of blogging. Big goals are great, but balance them with smaller goals like "posting once per week for a month" to give you and your students a sense of accomplishment.
5. Creating too many blogs too soon:
Sue sees this one more than I do because she is an administrator for Edublogs who responds to users help requests. The problem here is that teachers set-up many blogs either for themselves or their students without being able or ready to manage all of them.
I'll be covering these topics and many more in my upcoming webinar series Blogs & Social Media for Teachers and School Leaders.