Introduction to script writing: I have just started writing GuiXT scripts, including the use of InputAssistant. What do you recommend I do to become more familiar with this?

You could start with our tutorials. I suggest you try them out in your SAP system and maybe play with some variants. More complex examples can then be found in our "Examples" section on our homepage. The "Tips&Tricks" section is also worth a visit.
Some of our partners also offer inhouse training on our components; please contact us for additional details. Also, for courses in German offered on a regular basis please check here for details: http://www.koehn.ch/guixtschulung.html.