Most designers are very careful about registering copyrights for their designs. At least most everyone KNOWS they should be very careful. But life gets in the way, you get busy and bogged down and sometimes the registration fee seems just a little too indulgent when you look at your cash flow.
But trademarks are very different.
Here's some advice via the design*sponge blog from Amy J. Everhart, founder of a Nashville, Tennessee, law firm
to counsel clients in the creative industries, entrepreneurs,
inventors, business owners, and others in the areas of copyright,
trademark, entertainment, the arts and the Internet. She is the author
of the copyright, trademark, and entertainment law blog “Lightbulb
Moments,” located at www.aeverhart.com/lightbulbmoments.
Amy says, "Trademark issues can arise in several contexts in the design world.
You might use a trademark to identify the source of a product, such as
a line of note cards or a piece of jewelry. Or you might use a
trademark to identify your business, such as an online store or a
design firm, where you sell your artwork or provide your design
services. (A related concept is trade dress, the distinctive color,
shape, packaging, design, or other visual characteristics of a product
that identify the source of the product, such as the distinctive shape
of the Cola-Cola bottle. David Yurman has successfully sued on Trade Dress issues.)
Below linked is some of the trademark basics every business owner should ponder.