Before you read any further, I would like to point you out to this Oatmeal comic. I have no desire to reinvent the proverbial wheel; this comic is the most effective way to deliver the message. As you can see, Mr. Inman actually pulls a lot of these anecdotes from his own experience as a web designer. Sadly, this is what we HTML Luddites put our typical freelance web designer through.
I'm actually writing from the perspective of a client, and these lessons were culled from several years interacting with web developers of different levels of experience and skill. A great working relationship with your web developer will result in successful web projects with the least amount of time and hassle.
Allow Them to be Artists
Professional web designers are artists. They have their own sense of style and a grasp of the fundamentals of design, at the least. If you are going to reduce them to mindless layout peons, you might as well not hire one and craft the website yourself.
Be clear about what kind of look you want for the website (show samples from other sites, even), but allow them to use their artistic talents and skills to interpret your requirements and bring forth a design. Granted, most of the time it won't perfectly match the image in your head, but remember, unless you are a web designer yourself (in which case you should be doing it yourself), assume that your aesthetic sense is actually inferior to theirs.
Track the Content, Time and Progress
Always have a schedule and a site map to follow when you have a website project (or any other project for that matter). While your chosen web designer might have a lot of talent, it won't amount to much if the website is haphazardly planned and executed. Make use of all the project management tools you have at your disposal (I rely on spreadsheets myself), coordinate with your web designer and make sure you are both on the same page (literally).
There is also a danger of overdoing this and inadvertently choking your designer with too many meetings and status reports. Find a good balance in order not to take so much time to track and plan, resulting in more hours being dedicated to doing the project.
Provide the Proper Resources
Your web designer is not a miracle worker, thereby he/she cannot create something out of nothing. You must provide a sufficient amount of content, be it text, images, videos, and whatever else the developer might need to put the site together. This includes hosting, but worry not, you can get cheap unlimited web hosting, so there's no excuse to not pay your designer a decent rate!
It is also essential that you are available for consultation by your web designer, as there might be questions and clarifications he/she would like to make regarding your instructions or the content you provided them.
Stacey Thompson is a professional writer, marketer, entrepreneur, and a lover of weird little animals. She is based in San Diego, California, and is working with her gal pals in creating content and maintaining their site, Word Baristas.