Start by choosing a signage designer or 3D graphic designer specializing in the types of signs you are looking for. When preparing to hire a designer, you should come with an idea or general concept for your sign along with the message you want to be included. You should know in advance what type and size of signage you are looking for, as well as the source file you require.
Take a picture of your building or of the location where you want to install the Sign and ask your designer to create the concept art for your sign before fabrication. From there, the designer may create a digital mock-up so you can visualize how the finished product will look on or in your building.