My Drupal solutions are secure, well optimized, compatible with all browsers and comply to Drupal Coding & Security Standards. I follow the Best Coding Practices.
I do not alter core or contributed modules, instead create a patch & submit for review when it's necessary. I use Drupal API to build custom modules & themes and never hack anything. This is the phase of development when I seek my client's permission to contribute very generic code back to the community in form of a module or theme. It's always my client's call.
I'm very familiar with GIT and most of the available collaboration tools & services. I use pantheon to host the Drupal websites during the development. I can also work with AWS & manage the instances. I follow agile methodology, scrum & Continues Integration.