Do web design freelancers (I'm thinking individuals, not companies) typically do all development and design work themselves? What are the options for those with a strong base in back-end web development but less with web design, color schemes, layouts, graphic design, etc.?
As a freelancer myself, this is what I do. I normally talk to the person who is giving me the project and get myself a designer. The designer designs the UI and provides me with all the necessary HTML, CSS etc etc. Using that as the base, I change plain vanilla HTML to server components (ASP.Net) and I start working on the design and then start development. My design methodology is mostly agile, as in freelance projects (depending upon the scale), you normally don't have separation of phases. So agile works well for me.
Some people do try and do both.. and in most cases I have seen they do one well and the other... not so much. Designing and Programming generally take two different types of people. Often I've seen designers subcontract the programming work and focus on the designing aspects.
Personally I consider myself formost a programmer. I understand the basic aspects of designing web pages but I would rather let somone else deal with those details.
I'm up front about not doing any design work. I handle only the programming side. However, I keep all HTML seperate from the rest of the code, in easy to identify template files (e.g
header.php, footer.php, signup.php, etc), so its very easy for them to get a designer and have him change it without having to deal with much code.
I typically get all of my design work sub-contracted. That is, I'll hire a designer to build a photoshop version of the site, usually getting it 90% of the way there and then either get someone to cut up that design into HTML & CSS, or do that myself (depending on a number of factors).
There are many options for getting the initial design. I tend to use the same designer that I've used in the past, but you can use sites like 99designs.com or more generic freelance sites like elance.com to find designers. I would tend to prefer the designer-specific 99designs.com, they're more expensive but the quality is generally higher.
In the past, I've also sub-contracted out the HTML/CSS cutting, but I find that is more hit-and-miss than the designs themselves. I usually prefer to do the cutting myself, since I can tailor the HTML/CSS to fit better with the server-side generation of the HTML. I find that many companies which provide HTML/CSS cutting don't take tweaking or modifications into account and making changes to the layout or slight tweaks later on can be very painful. I've been burnt by that often enough - it's ended up costing me more time tweaking a badly cut design than if I had just done the whole thing from scratch - that I don't even bother much any more.