Really, the easiest way to learn to script is to keep close tabs on EasyUO and their Wiki for questions about syntax. But when it comes to actually scripting, nothing beats taking an existing script and trying to understand it line-by-line. Also there's some great tutorials out there.
There's lots of tips and tricks found here, at WinUO and EasyUO so you should always keep an eye on the forums because there are many great scripters out there who do share their wisdom.
Finally, if you do script in ScriptUO, I have included EasyUO Wiki help so if you have a question about general command syntax, you can easily call up the right information.
