The most important thing is to look critically at your tree when preparing for a bonsai show. This will illuminate problem areas that need attention.  Excess wire should be removed as well as dead leaves and yellow or brown leaves on trees not in fall color. The pot should be cleaned, recommending using a Brillo pad moistened with either alcohol or paint thinner to scrub the pot.  One then rubs the pot with a rag dampened with walnut oil.  Take care to wipe excess oil off by a final buffing with a clean rag.

If you are planning to enter a Juniper in a show, delay trimming the foliage until a couple of days before the show since the trimmed ends can turn yellow over time. Secondly, if your show tree has an ant problem, move the tree to the other end of the bench because the ants are not smart enough to follow the tree.

One should also consider the top dressing the soil of your show bonsai.  The basic reason for top dressing is to provide a transition of color between the edge of the pot and the trunk of the tree.  Dark trunks require a dark top dressing which is usually finely screened dark lava with some fine akadama to adjust the color.  Prior to applying the top dressing, the soil should be brushed to remove the relatively large particles by using a flat trowel to tamp and smooth the applied top dressing. Once the top dressed tree is watered, some large particles in the soil can emerge and should be removed.  After the show the top dressing can be left on the tree since it is mostly inert lava.

Moss can also be used as a top dressing, especially on a tree with a dense canopy which provides shade under the tree.  Moss can either be applied as a flat sheet, or as many small quarter-sized pieces wadded up.   The latter method gives an uneven surface to the moss which can be attractive.   In both cases, the moss is tamped into the soil to give good contact for the moss to grow. A mixture of moss and top dressing can also be used.