How do I decorate a log cabin stairway?

Pine garland with pinecones and burlap ribbon

Are you looking for Christmas decor ideas?

Since the logs have so much character and texture, I would decorate with simple things such as textiles or little whimsical craft items.

Potentially lights and garland

I agree with above comments. Use garland (live if possible) as the base to drape on the stairs. Then add red bows and ribbon. And next are simple snowflakes and hand made ornaments. (Dried orange slices and cinnamon sticks will give the house a great aroma).