Use color to focus attention on your main selling features and to improve the perception of quality. Two colors are better than one, and full-color printing is better yet.
Using a glossy paper will often make your brochure look more professional.
Avoid the temptation to try to jam too much information into a small space. In good brochure design, less is more.
Don't overlook the value of white space to bring a clean look to your design and to help accentuate key selling points.
For readability, consider using a serif type for body copy. Studies have shown that serif type is easier to read. Sans serif type is good for headlines and subheads.
Other Good Ideas:
If you will be mailing your brochure as a self-mailer, consider applying a coated finish (varnish) to the printing. The coating will help prevent scuffing -- ink being rubbed off by the post office's mail-sorting equipment.
For the best impression, consider mailing your brochure in a matching envelope.
For a unique sales and marketing twist, consider applying a small label somewhere on the brochure to draw attention to a special feature, special pricing, a sales rep's name, or a toll-free number.