For me, it has always been best to learn by doing. Think of something you want to build and go for it. You'll certainly make mistakes but don't worry about it; the web is pretty forgiving on a small scale. When you need general help, try asking a question on SitePoint. There's StackOverflow too, but I feel like SitePoint has more a learning environment while StackOverflow is just a place to get answers.
With every project you complete, you'll discover new and better ways to do things. Just be open about asking questions and showing your code. If you ever find yourself thinking there's a better way to something, there probably is, so go ahead and make a thread on SitePoint.
To prove I'm not making all this up (assuming this link works), this is all of the threads I've made on SitePoint in ascending order: http://www.sitepoint.com/forums/search.php?searchid=4499370 . Added disclaimer: In October 2005 I was 14, so excuse any poor writing in those posts