Before coming to Ameripay's Software Engineering department, I used to do consulting. Because with consulting, everything (such as what software you have licenses for) is project-driven, my software was often on the cheap. Clients and managers were very hesitant to pay for licenses for "frivolous" software, especially with the previous IT recession. Therefore certain things, like editing Xml Schemas, I often did the harder, manual way. For simple schemas this works, but it just becomes draining (You can learn the basics of Xml Schema at the online W3Schools).
Now I have XmlSpy installed, and it's great if even just for the schema editor. I've heard many good things about this popular tool, but never got the chance to check it out myself. The help section even has a step-by-step tutorial. It looks like Altova even offers a free XmlSPy Home Edition to get you started.
Yet another tool I wish I had had before.