In the Riker display cases use a colored felt cloth or velvet to highlight the items in the case.
In the display cases that the glass top can open, get a couple pieces of clear plexiglass to put on the sides to prop the top so it will stay open. If needed, get one for the back also.
Even some colored thin foam in the case will show the relics or coins much better than the standard white polyesther foam.
A small printout of info from internet research of an item..... be it a certain caliber bullet, an old watch, even a common date Mercury Dime, placed next to the item, will give a more professional look to the display.