I studied this and have been practicing my entire career. Well designed databases are critical to an application. See: Relational Database [wikipedia.org]
I also studied this and use it as appropriate. See: Objection Orientation [wikipedia.org]
I aim not to be "out there" in terms of design. A simple, well known design is easier to understand for those that have to work on a project in the
future, myself included. To this end I strive to use design patterns (but not rigorously).
Visit, for example, Patterns for PHP [patternsforphp.com]
I subscribe to the DRY principle: Don't Repeat Yourself. Essentially this is doing something in one place only.
I've been doing web development since 1999. I started developing web applications in ASP while I was doing technical support at Telkom [telkom.co.za]. I built an application to pull records from our fault management application and put them on the intranet. It became quite popular and was soon in use throughout the country.
In 2000 I started working at Krazyboyz Digital [krazyboyz.co.za] as a web developer. I was the second web developer to work there. In 2000 websites were really starting to become dynamic, so the work was growing. I moved from junior developer, to senior developer, to team lead to de facto Development Department manager. I was involved with the hiring of about six people and ended up with five developers in my "department" (a company of 15 people is too small to be walled off into departments).
As one who doesn't like doing the same boring thing repeatedly, I slowly built up a content management library which advanced little by little with each new project. It became quite robust, although by 2006 classic ASP was really showing it's age (and was frustrating to use if you spent any time working with OO languages). I ported it to PHP a few times but since our primary hosting server didn't have PHP on it, things never progressed in that direction.
I started freelancing in my spare time, both for a change of scenery and for a new set of challenges. This became a full-time pursuit in 2007. One of the things that inspired me to take the risk was this quote:
"It is not the critic who counts: not the man who points out how the strong man stumbles or where the doer of deeds could have done better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes up short again and again, because there is no effort without error or shortcoming, but who knows the great enthusiasms, the great devotions, who spends himself for a worthy cause; who, at the best, knows, in the end, the triumph of high achievement, and who, at the worst, if he fails, at least he fails while daring greatly, so that his place shall never be with those cold and timid souls who knew neither victory nor defeat."
Theodore Roosevelt