I took several existing pairs, took their measurement and did an Excel-Spreadsheet. Then, I optimized some measurements (i. e. higher waist etc).
I sent Luxire several photos & they did a perfect job doing everything I want (except for the useless left belt-loop, but that was also partly my fault).
Measurements worked out really good for the first try, I would recommend the spreadsheet-method for everybody.
The excel spreadsheet method is the one I've espousing for both pants and shirts after I used it for my first pair of pants. It works...period. It is an investment in time upfront though so be forewarned. Once dialed in, it's great and increases confidence in ordering more expensive trousers.