Lacing a shoe with a single lace is commonly known as straight bar lacing. This popular lacing style eliminates any diagonal crossing of the laces, leaving only horizontal runs. By routing the laces under the eyelet bridge as opposed to crossing over the tongue, a clean and unique look is achieved.
Insert the tips of the lace down through the tops of the lower set of eyelets. Grab the ends and pull the lace evenly though.
Set the shoe on your lap with the toe facing you. Route the left lace tip up to the next eyelet on the same side, under the bridge.
Run the right-hand tip under its side's next eyelet -- skipping it -- and up through the following one.
Route the left-hand lace tip directly across to the opposing eyelet. Run it down and through.
Cross the right-hand lace over to the opposing eyelet. Push this down and through.
Continue the process, alternating running the laces across and up until the ends reach the upper-most pair of eyelets.
This technique looks cleanest when using shoes with an even numbers of eyelets.