Select a stencil for your chosen letter. You may purchase a premade letter stencil at a craft store or create your own by choosing a letter and font on your computer, enlarging the letter to the desired size and printing.
Position the stencil on the foam board and carefully cut out the shape of the letter with a craft knife or other sharp cutting tool to create a wreath base.
Trim greenery to desired height with scissors. Shorten or remove stems, if necessary.
Arrange greenery on the wreath base in a visually appealing pattern before attaching it. You may apply as much or as little greenery as desired, but make sure to cover any visible areas of the wreath base.
Attach greenery to the wreath base by inserting the stems directly into the foam or securing them with hot glue or floral wire.
Examine the finished wreath for bare spots or areas that need additional trimming and make any necessary adjustments before hanging.
Hang the finished wreath with ribbon, if desired.