Good training resources are worth their weight in gold. There are plenty of well-known online schools, such as Lynda.com, Udemy, and Code Academy. Others are easy to miss. Below are some services that I've found very useful, at a good price.
Cost: under $30/month.
This site is operated by a very clever techie indeed. He explains important fundamental concepts in simple terms. Have you ever wondered how to use PHP to 'scrape' content from a website? Or how AJAX works? He never loses sight of the handful of critical concepts upon which the http protocol is based, such as the all-important XMLHttpRequest Object, which is a primary method for web pages to request and import external data. Jason and Object Oriented Program are explained in the clearest possible terms. Lessons are brief, averaging about 12 minutes, so you can repeat them several times until it sinks in. He also covers the top 100 PHP commands, which might help any aspiring programmer get over the hump.