Fall centerpieces created in silk can last a long time. I like using higher quality artificial flowers, as they tend to be wired. The cuts of the fabric is sharp and the flowers look realistic.
The ficus stems I'm using are going to be clipped apart in smaller laterals for easy insertion. Be sure to have a heavy pair of wire cutters, as some stems can be quite thick and hard. If you have a hard time cutting a stem, nip it slightly, rather than trying to cut the entire stem. Nip the stem again and again, and then simply bend the flower stem until it breaks. It saves a lot of straining with your hands.
Fold a portion of the stem wrap over the lowest lateral (the joint between the leaf and the wire, and pull down. This stretches the wire and causes it to get sticky and cling to itself. Keep pulling down gently with a stretch motion while turning the wire stem.
You should have a fine, wrapped stem that can be now inserted into the foam.