To preview an invoice before sending:

1. Open the invoice (it must be saved first)
2. Click the "Preview" or PDF icon button
3. Review the layout, amounts, customer details, and branding
4. If changes are needed, go back and edit
5. When satisfied, send or download the final version

While the preview is open, click Change design in the preview header to jump straight to the invoice design settings. You can adjust the look of all your invoices and quotes, then return to the document you started from.

Tip: Always preview before sending - it catches formatting issues, missing details, and incorrect amounts.