I second networking. Get to know other designers and scripters, but most importantly, focus on developing your skills with
HTML,
CSS, and
PHP. After you get the basics down, avoid w3schools like the plague. Before you meet & greet with other designers,
follow tutorials online. Understand you're probably going to be spending a lot of time learning from other designers before you're ready to start selling your own work. Build a portfolio, even if it's full of hobby work you never got paid for. Once you feel your skill is on par with your peers and you start selling your designs, add them to your portfolio.
There are other things to focus on that can help.
Color theory is one of them. There's nothing more important to a web designer than knowing which colors compliment each other and how to effectively use color to draw or deflect attention. Study
navigation design to ensure that you know how to provide an easily browsible website without confusing new users. Lastly, check out some
really, really bad examples of web design to know what you should avoid.