Amazon EC2 instance naming is done by using Tags (http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html)
We do not provide best practices for naming, it really depends on your application, project, organisation.
Some customers are using tags per
- environments (dev, tes, prod)
- org unit (marketing, hr, tax...)
- project / app name
- expiration date (for temporary resources)
- cost center code
- ...
You can combine all these, up to 10 tags per resources
Seb