Know what marching groups you are ordering uniforms for. Many marching bands include not only the instrumentalists, but also a dance troupe and a flag corps who need matching or complementary uniforms. These auxiliary marchers, as well as the drum majors, require special uniforms to match your custom design.
Pick a color scheme. Three colors is ideal for a marching band uniform, with at least one basic color like white, black or navy blue. School colors are usually an easy pick, but if the school only has two colors you'll need to choose a third for the uniforms.
Decide if you want the uniforms to fasten in the front or the back. Keep in mind that front-fastening uniforms are easier to put on, but back-fastening uniforms may look neater, and can still have buttons on the front to appear to be front-fastening.
Determine whether you want the uniforms to have a sash, embroidered cuffs, tassels or other embellishments, including a school logo.
Decide if you want the pants to have marching stripes or not. Stripes in a lighter color look good when the band is marching in step, but can also get dirty and dingy over time.
Order a sample uniform from a uniform supplier that offers custom marching band uniforms. Many companies offer customizable uniforms for bands and other organizations, and may even allow you to order several samples with different options to compare.