Design, an art and science. I have read more books than I care to remember on this topic. I have worked with other professional designers on sites as well.
The goal of the design facet of the project, is to create a site you would want to brag to your friends about. But simplicity is your best friend. If a website has too many “bells and whistles” it slows down the page’s load times (bad) and hurts the users finding what they want (very bad). You also want your message/product/metric for success on the top of the page. This makes it easy for the user to find what you want them to.
Use colors that communicate your message, bold – red, trust worthless – blue, vibrant and youthful – green there are a ton of combos.
Consider round shapes, html allows you to make awesome circular images on a page.
I would like to note there are several books that speak strongly on this subject; Don’t Make Me Think by Stephen Krug and The Principles of Beautiful Web Design by Jason Beaird.
Both of those books inform a fair amount of my UI/UX philosophy and the cool stuff I love to add in to the websites that I work on. Designers or people who present them selfs as web site designers, may or may not be graphic artists as well. So, if you do not have your own logo, they might refer you to a graphic artist, because logos are not something they are good at.
Another thing to think about with the design of your site is images, do you want images done for you or your company or would you want to use stock photography. I personally like designing sites using images I have captured or royalty free stock images when getting the shot would require an undue amount of work.