When creating a new project, it would be cool to ask user whether is this a Team Project or an Individual Project...
If he selects "Team Project" he can simply put in the emails of the team members and so the Team Members would get an Email and Also they would have that document in their profile as Owned Document.
If he selects the "Individual Project" he can simply continue and make the symbol and later if he wants he can add users as "Can Edit" in the share option. Like it is now.
The reason for this is that it would look more dedicated.