See here the mistakes to avoid when you are creating a naming convention for your marketing UTM tagging:
Very often advertisers don’t use any specific UTMs on tagging their marketing campaigns. Although they have implemented a solution like Google Analytics on their pages, many times, the information how to use UTM tagging is not communicated to all the marketing departments, in all countries, and because of that, the online marketing campaigns do not have any tracking.
Tagging Internal links
Many times I see UTMs inside the websites, specially on the front page, because content managers wanted to view on Analytics where the users are clicking. This will mess up all the data about the external traffic sources, as these UTMs will override the information about the external traffic. Using UTM tags inside the website must be avoided 100%. Content managers can see the path that users are are making on the behaviour section of GA (Google Analytics).
UTM tags are case sensitive. That means you should implement a rule for UTM tagging, writing all in upper case, or writing all in lower case. The recommendation is to work with lower case as BING and GOOGLE are using lower case on auto-tagging. You should definitely have this rule in place, or you will ending up having different campaigns on Google Analytics, one in upper case and one in lower case, or even more just because someone decided to put another letter in upper case.
Freestyle UTM tags
You should have a document, like a spreadsheet on Google Docs, shared with all the stakeholders, with all the networks and specifications, so all the users in your company will know the UTM parameters to use.
Long Campaign Names
Avoid having long campaign names. Create a first naming convention and then try to clean up all the information that you do not need. Here a recommendation: country_brand_channel_provider_motive. The brand for example, is only necessary, if you have more than one brand in the company.
Consistency in the tagging
Remember that consistency is very important because that is the main factor that will allow you to do an analysis about cost-return (performance). Avoid to name medium as cpc, paid, etc.. Instead use the channel: social, display, email, etc.
Communication and anticipation
When implementing, think on possible future problems on your naming convention, and try to anticipate the next steps. Communicate, with all the stakeholders, one by one, the reason for each naming. If everyone is involved in the process, the adoption will occur in all the marketing departments and you will have a clean tracking on your Google Analytics.