When getting started on a design, it's often helpful to begin with simple mockups or wireframes.
V7 users can create mockups or wireframes in Freehand using the wireframe add-on or by using the wireframe template from the Freehand template gallery. For more information on Freehand, check out the Freehand Getting Started Guide.
When you need to move beyond simple mockups, InVision also has a design tool called Studio, which allows you to create robust prototypes with beautiful interactions. Check out our Studio Getting Started Guide.
If you choose to use a third-party mockup or wireframing tool, you can always upload your exported file to InVision as a prototype where you can collect feedback from your team.