When creating your Contact Groups it is good to think of it like tagging your Contacts with a label - or if your young enough it's like using a #hashtag. It makes it easier to find a collection of associated Contacts.
With this in mind it is good to have a naming convention so it is both easier to find and easy to remember for the rest of your administrators. TidyHQ by default uses the following and we would warmly suggest you follow something similar.
Use <Year> <Group Name> so something like "2017 Event Sub-committee" or "2017 League Team".
Now when you come to creating that Email Communication you can just start writing "2017..." and it will show you the Groups associated with them quickly 🚀