Before you can start creating a template, be sure to add all of your services to the list of items. It takes a few simple steps, check out how it's done here.
Once you've got those added, go to the Invoice Templates tab and open up New Template. Here is where you can build a specific invoice that would be available to send out every time the same type of service/session is booked.
Fill out the text fields in regards to the package you offer. You'll find all of your items in the drop-down menu under the Item Name field. You can add as many as needed by selecting the + Add Items button.
You can edit or delete your invoice template at any time. You can also set if it's taxable by clicking the three dots next to each invoice item.
Also, note that you can add a memo for that invoice template, like "Thank you for your business."
Hit Save, and you're done! Your new invoice templates will be available when creating or editing a quote or invoice. You can find these invoice templates by clicking the Templates dropdown when creating a quote or invoice.