Welcome to the Asana Community Forum @Libby_Thomas 
For projects we use colours, icons and emojis. We love emojis 
Here is an example:
How we structure it is mainly by:
Colours: we use colours to define what project groups something belongs to + some internal colour structure we defined
Emojis: we use emojis to define different categories such as marketing, design, customer support, paid marketing, etc (Like for example for anything related to reviews we use the star emoji, for any projects related to our blog we use the book emoji, etc).
Names: Obviously names are key also. Since we are working on tasks for various countries we have a specific naming structure in place such as EU-PROJECT NAME-Marketing for example