At it's core, our craft is about two things: Content & Interface (for that content.) Your content is the reason your site exists. The whole task of Web design is getting the users of your site to the content they need as efficiently and pleasantly as possible.
As such our core philosophy is usability, or "user-friendliness."
Over my 18-year career, I have picked up five key principles that maximize usability:
1. Don't Make Me Think.
This is the sum and goal of usability-focused design. Our work is to minimize work for the user, to minimize thought, to seek to make every aspect of the site as immediately evident as possible. This is accomplished primarily through excellent information architecture, minimalistic graphic design, and a deep understanding of the relevant industry research, and specific testing of your site's user base. The other principles flow from this principle.
2. The smallest effective difference.
A call to minimalism in design. A combination of Edward Tufte's work in "Visual Explanations" and Dieter Ram's 6th and 10th principles of design: "Good design is honest" and "Good design is as little design as possible."
Focus on the essential. Do not seek to manipulate the user or obfuscate what is really present. Do not burden the design with non-essentials. Design is as-subtle-as- possible, while still remaining effective.
3. Follow Convention
Because we are seeking to minimize, or when possible, negate, the learning curve involved with using your site, we should follow current Web design conventions to the degree that they help a user find what they need on your site.
Note: because much Web design is done apart from research and usability-thinking, there are some "popular" Web design trends that are copied between many popular sites that do not actually serve this purpose. These should be avoided.
4. Universal Usability
Every user of your site should have full and unhindered access to every function of your site, regardless of what device, platform, technology, or assistive device they are using to browse it. W3C Web Standards exist to ensure that this is possible.
5. Form Serves Function
An old Shaker proverb that ought to be applied to the Web says "Do not make something unless it is both made necessary and useful, but if it is both necessary and useful, do not hesitate to make it beautiful." This is the final principle on purpose, but an important one, and an important aspect of craftsmanship.
In line with the above principles, we should also seek to make sites beautiful for our audience. These principles all lead us to focus on typography and relevant photography and videography as our primary design elements.