See your app as a various set of features and try to group these features in a hierarchy. Root-level features can be the key areas of your app which serve as entrypoint for rest.
Take a look at this example:
Assume you have a mailing web app (like GMail), follow suite structure might fit your needs:
For a very large app, you might have various microservices and root-level suites might be named after each microservice.
So it depends on your preferences but for most cases we recommend following structure of the above example as it fits 90% of use cases.
Some DO's and DONT's:
Do not specify suite names with info related to execution. For example, "IE Tests" is not a good suite name. Suite name needs to strictly tell a user the part of app it refers to, not where or how to run it.
Stick to 3-4 words for suite names. Longer name = More room for interpretation or boring names.