These days things change quickly. Most of the emphasis should be on the initial launch and the longer-term aspects should be left vague to adapt to circumstances.
2 - Ignoring the culture
You can have the best plan in the world but if the employees can't carry it out or aren't going to get onboard then it's a waste of time.
3 - Failing to appoint a project manager
The project manager is the one who bothers people to make sure the work gets done. Without this person plans fall apart.
DIGITAL STRATEGY ISSUES
1 - Taking for granted the level of literacy among the planners
In the government many people are firewalled from social media, there is little training available, and its use is discouraged. However the audience we are reaching is hyper-sophisticated. So when you're planning a digital stratgy you have to find a way to bridge that gap, either by training the decision-makers or getting them to delegate decision-making to more knowledgeable people.
2 - Over-focusing on the tools and under-focusing on communication principles
Some people get so caught up in the technical tools (especially if they're using them for the first time) that they forget basic rules of communication. Communicate first, technical tools second. Even if you use only one (let's say a blog or Twitter), but you use it well, it's better than using a dozen badly.
3 - Using words like "pushing the message out"
If I ever have to hear the words "pushing the message out" one more time I am going to throw up. You don't give birth to a message. You start a conversation. If you're doing a good job the comments will do the work for you.
4 - Related: Doing the equivalent of cutting and pasting a press release into a blog post
In social media we don't "write content," we talk like normal people to other normal people.
5 - Failing to take advantage of RSS feeds & sharing
Nobody has enough time/people to write tons of content and "push it out." However there are hundreds of thousands of people interested in what your agency is doing. If you write good content and make it available via a ShareThis type capability they will automatically send it to their contacts and friends. RSS is important here because if you show people how to get your content easily and automatically through a reader (such as Google Reader) it's really simple for them to see all your headlines, click on what they want, and send it forward. People actually love to do this.
6 - Overfocusing on words, underfocusing on pictures and video
People love video! People love pics! People don't read.
7 - Encouraging social media use among communicators but nobody else
This is really silly. You have all these people working for you - make it OK to share content. The Coast Guard does a good job of this and their social media policy encourages it.
8 - Measuring the wrong things
There is too much emphasis on quantitative metrics and not enough on qualitative. You have to read the comments in the context of discussion boards, twitter conversations, etc. Get the flow. This requires balancing the presentation of fact with the drawing of conclusions. It's OK to editorialize when you're assessing the impact of a digital strategy.
9 - Executing on bad ideas
If a strategy is going to fail, it will fail worse on digital because it's there forever and you can't just change things in a couple months when you get your act together. It's OK to pull the plug at the last minute.
10 - Last but not least, copying print to digital as if you could transfer it
A print ad is a print ad. A widget is a widget. An app is an app. A tweet is a tweet. All of these are totally different. You have to adapt the strategy to each unique environment. The only thing that has to stay consistent is the brand - how you apply the organization's image should be the same across all environments. (E.g. if you're a youngish cheeky innovative brand your communications should have that look and feel everywhere.)