One of the nicest Christmas decoration themes is what last year we called winter wonderland. First read the article itself and then come back to this post to see a few examples as to how to achieve the look.
Here is a picture that identifies this theme:

It is important that you use as many natural objects as you can. Go for a walk in the nearest wood, forest or park to collect twigs, berries, acorns, cones, nuts, seeds and leaves. Dry these out for a couple of weeks - you can then decorate them to create wreaths, garlands and ornaments, such as these:
This is a preview, read Natural Decoration
in full.





