It is easy to make simple spelling and grammatical errors on your website.  You are so involved with the design and writing the copy, that you can overlook small errors.  Once you have your website up, or a new page completed, step away.  Give it a day, and then go back and look at your site with fresh eyes.  Take the time to read through each page, even read the page out loud, so you can catch any errors.  It is a simple process, but many overlook the importance of proofreading your website.  You want your website to represent your company in a professional manner, and having spelling and grammatical mistakes takes away from that.  If you have a hard time catching these errors, ask a friend or family member to proofread it for you, or hire a professional.  This one simple step can really improve the appearance of your website and your company.