When I decide to do a custom order, I do half up front and half later and they pay the shipping with the final half.
I don’t usually do custom orders as they can be stressful and frustrating as other girls on here will also agree.
Also I would only do sculpts that I want to do. Either list which you would want to work with or say if you have an extra Summer Rain kit, set up a listing for a Custom summer Rain- customer gets to choose hair color.
And charge more for customs than you would for a sold doll. If you sell dolls for 400 then charge 500 because this is a special service you are offering.
Charge extra for belly plates too of course
Give yourself plenty of time to complete to Doll so you don’t get stressed.
Make sure customer knows the deposit is NON REFUNDABLE as it is used to purchase art materials