What qualification and/or skills should I look for while hiring a web designer?

You need to consider four separate things. (And most companies completely skip the last item, which is a big mistake.)

1. The designer's portfolio- what does his or her work look like? If you aren't impressed with what he has done before you are unlikely to be happy with what he does for you.
2. Performance references. Ask for references and check them!
3. How well does he code his web sites? Ask for the url of a real live web site he has produced. Run it through one of the free on line HTML validation web sites. There should be no errors. Errors will cause display problems in various browsers and indicates a lack of attention to detail in this person's work.
4. SEO coding experience. You can not build a web site without understanding basic SEO techniques. A competent designer understands the basics of SEO as it applies to web site design and uses that to your advantage.

I have helped business friends improve their web site rankings. (This is not a service I offer!) They have beautiful web sites that perform wonderfully. But even though they have been on line for 5 years they show up 500th on Google's search for their most common keyword. Google can't find them or ranks them at the bottom of its search because the web designer did not have a clue about basic SEO techniques.

Typically a web designer is involved with the way a website looks. This will involve HTML/CSS. A web developer on the other hand is concerned with how a website functions and should have a solid understanding of HTML/CSS, as well as a programming language like Python or PHP and Javascript. The specific skills necessary will depend on your website. Your developer at least needs to have a solid understanding of HTTP, and probably database design. Any any web developer worth their salt will have these skills. You may be able to find someone who can do both well, but that is not likely in my experience. For instance, I consider myself a developer. I can make a fully functional website that does everything you need it to do. It will however be very very ugly, so I leave the design part up to designers.

All of what Gary E mentioned are critical. Another key point in my expereince is your designer must understand what the goal of the website is. If your designer is not asking you that critical question - then you need to look elsewhere. :) Some usability and conversion optimization understanding and experience is essential for a successful website.

I work in the field and I don't know of any individual that has all these skills (design skills, coding expereince and has a good understanding of how seo, usability and conversion optimization fit into a design). A company that has a complete team will likely be the best option. Although, that would come at a hefty cost.

I agree with all these statements. I am a print graphic designer and starting to build Web sites for myself and for clients.

What I am finding is that I/my studio needs 3-4 layers or skills sets to do a good job. Each aspect -- to be done well -- is a laborious process and so the best results are usually created by specialists in each area.

1. Visual design: the design is planned as wireframes in basic design programs such as Illustrator, Photoshop or Fireworks. Apart from the design style, usability and conversion is an important point of discussion here. Is the information organized in an intuitive way? Is the most relevant information for your customers easy to find? Is your telephone number or email in an obvious place?

2. Web layout: This is where the visual design that resides in a design program is changed into HTML and CSS code so that it can be viewed on a browser. Sometimes a good visual designer and a good Web layout programmer are one in the same. Sometimes not. At any rate, they are two separate steps in the process. This is where you want to make sure that the basic aspects of SEO are implemented (see the link below).

3. Back-end development: This is the aspect of web development that does not relate to the way the site looks but, as Jacob mentions, the way it works, such as content-management, databases, etc. Here I am finding developers that really focus and enjoy this aspect do not like to think about the two previous aspects related to Web site appearance. They can perform both functions but I lose a lot of time reviewing and correcting their work. So I am now separating these functions when I hire freelancers.

4. SEO/usability/conversion. I agree that a good Web designer or developer will have basic notions about proper SEO that at least conform to the dictates of this link: http://www.clickz.com/3635782.

Beyond that, especially when talking about lead generation and conversion rates, you definitely want a professional digital marketer on board. At any rate, a discussion of SEO/usability/conversion needs to be present during the Web design/development process to make sure your money is well spent.

Good luck!

You need to nail down what your requirements are for your site. Prioritize: usability, design aesthetics, performance/database usage, and any marketing/SEO needs.

Shop around for designers and take a look at their portfolio. You'll notice right away which ones are appropriate for you and at a closer look, get an idea if they have the technical skills you need. Follow other recommendations for code review.

DO NOT hire someone without seeing them at work. Tell them ahead of time (this isn't a pop quiz) to bring a laptop or have a way to connect to a home computer (Go to my PC) during the interview. See if you can give them a one web page assignment. Take a page you don't like about your site and see what they would do with it. If they can't type code quickly, bad sign.

Ask them about the tools they use. I would expect very passionate responses about their computer, development tools.

Here's what we look for: - Talent - Idea generation - Ability to code their designs to at least a basic level - Attitude - Self motivated - Attention to detail - A desire to keep learning - Good research skills - Communication skills - Team player - Interest in human behaviour - A love of good design - Outside passions - A work/life balance - Good sense of humour

Hope this helps. I appreciate many of these apply whatever the role but I believe personality traits and life skills are just as important as talent and creativity.

Also make sure that the freelancer provides you with detailed contracts which equally support both parties.

His view on how to find what's more user friendly, his expertise in latest technology such as html5 and one of the Ajax toolkit like jquery or gwt