If you're interested in customizing your booking form to best suite your business, you may be interested in uploading custom icons for each of your 'extra services'. 

Example of Custom Icons for a Cleaning business' booking form:

To upload a custom icon for an 'extra service', go into the service and upload an image under the 'Service Icon' field.

If you wish to find icons that relate to your extra services, you may want to purchase 'icon packs' that are for sale online. Alternatively, you may find icons on fontawesome.com or hire a freelance artist on Fiverr to create icons for you.