What makes a website great is efficient organization, clear navigation, and most of all a great message. The first major challenge to creating any website is organizing the content. It's important to have a pleasing design, but all the pretty stuff needs to accent the structure – not be the structure. Think of it this way. If you paid a landscaping company to design a look for your front yard, and they simply crammed every trendy new plant and paver into the space between the the street and your house, you'd be looking fo a new landscaper. The point of landscaping is to accentuate the look of your home–not cover it up.
Now, let's say that you have your content organized into pages, posts, and menus. You know what the important pieces are. The next thing is to make sure that your content flows. You need to make sure that customers who visit your site experience your content in a way that is logical and effective. You also need to make sure that they can find whatever they're looking for in 3 clicks or less. In other words, you have to make it easy for your customers to engage your company.
Finally, and most importantly, you have to have a great message. No amount of organization or navigation will overcome the problem of having nothing to say. This is where most companies really struggle. You have to have more to say than, "We've been in business for ## years." You need to push beyond the jargon and the cliches. Nobody cares if you're a "full-service" whatever, and the internet is full of "one-stop-shops." Tell people what makes you different from your competitors. Talk about the aspects of your company that are truly unique and why you believe that uniqueness matters. If you can combine efficient organization and clear navigation with a really great message, you'll have a great website.