First go out and forage. Gather interesting branches with pretty leaves, seed pods, and evergreens. Think shapes that you want to use. I made a short centerpiece for the dining room table so I knew that I wanted it to stay low and wide. So I was thinking I needed some substantial base pieces, some long flowing pieces and some good filler pieces and lots of texture.
I used wet floral foam because while many of my pieces were already dried a few were still green and I wanted to make sure the centerpiece lasts as long as possible. Just cut the foam to fit in your container and add a few slits in it to help absorb the water. Fill will water and let set for 20 minutes or so checking to add water as needed.
Separate your plant material and start placing your headliners in the center. This would normally be my flower heads during the growing season. However at this time of year you may not have any flowers left. Instead, use some beautiful seed pods, pine cones or even some fruit. I used a combination of dried and green hydrangeas. Use floral picks for floppy plants to give them support. Next, start to add longer curvy pieces to the sides and fill in and around with your fillers (full shorter pieces that take up space). Be sure to turn the centerpiece around so that all sides look good, and your done. Add water as needed.
This arrangement should last for awhile but if some of the material wilts or looks bad just take it out and add something new. If you can no longer go out and forage try fruit and or ribbons tied up as bows.
Try it. I find it super rewarding. It makes you feel very creative and it really is easy to make a beautiful centerpiece. The best part is that it comes from your yard where everything it price.