creates transparency about your teams availability and enables semi-synchronized communication. We use Slack.
sharing files between team members enables collaborative working. For security reasons, the sharing-model needs to be user-based. Google Drive is what we suggest.
having a project plan is vital for delivering any project. Trello makes virtual project planning and tracking really simple.
creative work within a team is always a challenge. Using MIRO you have a virtual Whiteboard which allows real-time collaboration.
You can register and use all these remote work tools for free. Free usage is limited by volume such that small companies will pay nothing at all.