Start with a labeled property sketch
Divide the visible scope into named sections: front eave, garage peak, left return, entry columns, maple, wreath, and so on. Record measurements beside those labels. This makes it possible to remove or upgrade a section without reinterpreting one undifferentiated total.
Roofline
Use a field method appropriate to your training, equipment, property, and safety rules. Record linear footage by section, mounting surface, roof height, pitch/access constraints, power path, corners, transitions, and expected extension/lead wire. Do not turn a rough photo estimate into a precise customer promise.
Trees and greenery
For wrapped trees, document the method used to estimate strand count, the target wrap density, trunk/branch scope, accessible height, and strand specification. Count wreaths, garland runs, bows, timers, stakes, and custom pieces individually.
Separate quantity from difficulty
Footage describes scope. Height and difficulty describe production conditions. Keeping those inputs separate helps the price book stay reusable and makes job revisions easier to explain.
Close the loop
After install and takedown, compare planned quantity and labor with actuals. Update the price book or adjustment guidance when the same miss repeats.