Find a local store or craft store that sells Celtic-themed decor. Colored glass, intricately designed crosses, shamrocks and any item that has the Celtic knot on it can be used as Celtic-themed decor.
Design an outline of where your decorations will be. If you are decorating for a wedding, decide which decor you will use as the centerpiece for the tables, what decorations will be hung on the wall and whether you want to use Celtic-themed gifts for goody bags. The jewelry worn by the wedding party can also be Celtic jewelry to tie in the theme. If you are decorating your home using a Celtic theme, use large spaces of empty wall to hang ornate Celtic crosses, substitute stained glass for glass windows in your doors or cabinets and place shamrock decorations in spaces that are highly visible to remind you and your guests of good luck.
Create your own Celtic decor by drawing Celtic knots on thick paper and framing it. Carving Celtic knots into wood and hanging the wood on the wall or setting it on top of cabinets is also a great way to display original Celtic artwork. Shamrocks can be hammered out of thin metal and placed in the home for great decor as well.
Search antique stores and flea markets for unique Celtic decor. It is often easy to find Celtic antiques such as crosses or statues. Build your collection over time to decorate your entire home with a Celtic theme.