Keep the handrail useful
Place the decoration where people can still use the handrail comfortably. Before choosing a route, consider children, visitors and anyone who depends on the rail. Keep the walking surface and bottom of the stairs free of trailing foliage and cables.
Measure along the slope
Use the actual sloping length of the route, rather than the horizontal distance between the top and bottom. Add the shape of any planned loops and the length of the tails. String is useful for trying this without committing to a particular garland.
Plan the fixing points
Check the garland weight and use fixings appropriate to both the decoration and the surface. Avoid promising a damage-free result from a hook or tie without checking its instructions. Secure ends neatly and keep sharp wire ends out of reach.
Consider the light source
A battery model can reduce the need for a mains cable along a staircase, though the battery compartment still needs safe, easy access. A mains model needs a suitable cable route. Do not connect separate lighting sets unless their instructions explicitly allow it. Test the layout before adding extra ornaments.