What kinda show; all makes, OE stock resto, custom stuff? Different shows would need different things to stand out.
In general, details make things clean. Hose clamps without long tails, tie wraps that are cut back, service loops in visable wiring, insulated adel clamps to hold things in location, no wax visable in tight corners or body breaks, panels that are aligned consistently, lines and hoses routed in a neat fashion. It's the little things that differentiate a "build" from an assembly line, throw it together method.