I develop with best practices in mind and adhere to W3C standards. Not all browsers are created equal, so I ensure that any website I work on displays pixel-perfect in all of the major browsers (Chrome, Firefox, IE & Safari).
I believe that having a functional website is only part of the solution. Being found is just as important. SEO is an integral part of my development process.
Many developers overuse libraries and modules but I don't. I know how to keep your site/app lightweight.