As a graphic artist, one of the most difficult challenges is coming up with original designs.
The Monkey Buddha Archives:
The phrase "There's nothing new under the sun" sometimes feels all too true. You may think you have an original approach to a design, but with some research you may also find that something very similar has already been done.
On the other hand, graphic design is often a synthesis of existing concepts & elements, so it's good to be familiar with common approaches & conventions to dealing with design problems.
I saw this page on the Internet Archive that demonstrates some common looks and treatments of logos in corporate branding.
This is a guide on what to avoid when designing a logo, but it could also help with using elements that could be applied to more unique approaches.
For example, I'm posting the groups of logos using trees (above) & a 3D spherical element (below), but there are many more sets of similar logos shown at the linked page: