PHP or other language
I’m not going to preach about the pros and cons of different languages, suffice to say that any sufficiently advanced website is indistinguishable from magic requires more than just just static files to make it work. PHP is my language of choice (and has been for over a decade) but there are plenty of other options out there (Python, Ruby or even (shudder) .net)
Which you choose depends more on what is most comfortable to you and what support network you have to call upon. It isn’t generally a good idea to learn Python in a Microsoft shop for example unless there are other pressing reasons to do so.
Whatever you end up learning, you need to be competent in its use, make use of the extensions available (no point reinventing the wheel when there are dozens already made for you) and know how to use the online documentation. Coding style helps, but as long as you are consistent really isn’t that pressing unless you are working with others.
Even if you don’t deal with much front-end code yourself, perhaps you use templates, you still need to understand at least the basics of XHTML and CSS to make it easier for the front-end developers to deal with your output. At the very least your code needs to output well formed, correctly nested code. We mea
(note the lack of ending <p> tag and improperly nested <i> and <b> tags) an XHTML validator will help, but only on the finished output. They don’t work on fragments of code like this.
MVCs, frameworks and libraries
As stated above, and especially if you are getting paid on a per project basis, you want to reduce the number of times you want to reinvent the wheel. This is known as Don’t Repeat Yourself or DRU. There is no point writing yet another PDF library for example when FPDF, Zend_PDF, Pdflib and many others already exist (or docbook/ps via converters etc) and do an adequate job for most tasks. MVC or Model-View-Controllers to give them their full name are a concept (or design pattern) that allows you to separate the data access parts from the actual logic and the templates used in your projects. This is useful in a team based environment because the designer can design, the coders can code and the coders and DBAs can control the models and how they interact with the databases - it just tends to separate the roles more cleanly and make modifications at a later date easier. If you want to add sharding to the database, you can simply modify the models while keeping the interface the same and suddenly your app can be cluster aware. It’s really a win-win situation.
I use Zend Framework under PHP to provide a MVC and other libraries. I’ve tried Code-Igniter and Kohana and while they work, they either feel dated (in the case of Code Igniter) or just are poorly documented (in the case of Kohana). Zend Framework, while not trivial to get up and running for the novice, worked well for the way I work.
OOP is one of those things, you either love it or hate it. I personally tolerate it with a mild distain - but that is just me. (I predate the whole OOP revolution.) Put simply, OOP allows a set of related variables and functions to be pulled together into a single package called a class. You then can either extend the class in your own projects overriding or extending the various functions (called methods) or use it as is. The biggest advantage, especially when you are importing a lot of libraries is that unless you are careful, two libraries may have a function or variable with the same name. (This is solved with namespaces in the latest PHP versions) At best the interpreter or compiler throws an error, at worst one library may end up calling a function or trampling over the data from another unintentionally.
At its simplest level a regex is a way of matching patterns within strings. When used to their full ability, a regex can sometimes replace 10-20 lines of non regex code with a single line. They are often used in Mod_rewrite rules, input validation and searching for certain things within quanities of text. Learn them, use them and master them - they will save you a lot of time.
Even when working on your own projects, you sometimes wish you could turn back time and undo something stupid you did a month ago in some code. Your backups have been recycled and a lot of changes have been made since - it sounds like a lost cause. This is where version control comes in. Everytime you are happy with a set of modifications you check them in. The difference between the old version and the current version are worked out and saved. At a later date you can go back and see who made the change, when it was done and exactly what was changed. If you want to checkout a copy of the code as it was at this time, you can do that. This is almost essential in a team-based environment as it allows auditing of code in a more detailed way than simply looking at backups from a particular point in time. What if one of the coders inserted a backdoor into your code? Wouldn’t you want to be able to identify every other change that was made and check them for similar nefariousness?
As a developer you will often find questions and problems that you don’t have the answers for. You can try to puzzle through it yourself, but there is a whole world of people out there, many of whom have already solved similar issues and put their answers online. Being able to search effectively puts these answers at your fingertips.
Monitoring and SEO
A site is a success if it reaches its goals. It is hard to know if you are hitting them if you have no way of measuring the values the goals specify. Are you being seen by 100 people a day? Are you selling at least 3 widgets from your site a week? Does your advertising campaign result in increased sales and traffic? You need to measure anything that you need if you are going to try to set goals on these things - simple idea, but it’s suprising how few people ‘get it’.
SEO is related to monitoring your traffic in a similar way to energy efficiency is related to watching how much power you use. Unless you know where you are starting from and where you are now, you can’t know how much you have improved by and if you are paying for adwords or similar advertising, then how much each extra visitor or sale is costing you.
JQuery and other JS toolkits
The easy solution to this is to take a library that hides these differences and make it easy to write code once that will run on most other browsers. Jquery is one option, but not the only one.
In addition to this there are many libraries, shims and other utilities that make doing more complex things easier. JQuery for example has the UI library which makes certain tasks such as tabs and date pickers trivial to add to your page.
This isn’t an exhaustive list and I’m sure there are many things could be added to the list. If you feel I have missed something, please add it below in the comments section.