In Products & Services settings section you can set a few things to make your job easier.
First of all, in the Defaults section, you can set if by default all the products and services are commissionable. It makes your life easier because you don't need to enter it manually on every new product or service.
Secondly, you can add the Custom Fields, Custom Field Groups and the Products & Services Groups.
To do so, you need to press on the settings wheel at the top right corner and navigate to the Products & Services section:
This opens the Products & Services Settings window:
You can create the Custom Field groups to have some order for your Custom Fields. To add a Custom Field Group, press the universal add button (+) and you will get a pop-up window:
Enter the name for the group in the Name field. In the Order field, enter the order number in which this group should appear in the list.
Also you can create the Custom Fields for the Products and Services. Just press the universal add button (+) at the Custom Fields section and the pop-up window will appear:
Enter the Display Name of the Custom Field and choose a settings group that you've created previously. Also, select the input type from the drop down menu and enter the number in the Order field, describing the order in which this Custom Field should appear in the list of Custom Fields under the Product or Service.
In Products & Services Groups section you can create the groups for your products or services. To do so, press the universal add button (+) at this section and the pop-up screen will appear:
In the Group type field choose for which items this group will be applied, enter the name of this group and select the income account from the drop down menu if needed.
When the group is created, this will appear in a Group drop down menu when you create a new Product or Service: