Hey I have now seen loads and loads of questions about this in the short time that I have been here. While some have been genuinely interesting, most of them have been asked because ppl have been afraid to experiment/lazy to find out. No offense to anyone intended

. What I'm saying, is everyone has to start somewhere, just by looking at what files u have and trying to figure out what they do, how, why and when the game uses them. The worst that could happen is that u have to reinstall the game.
If you are really worried and don't want to have to reinstall, just make backups of the important files: dialog.tlk, chitin.key and the worldmap file if u wanna mess around with area editing. You could always make a back-up of your entire override folder (seeing as the patch installs some files in there) and just delete everything if your game cocks up and start again with the backed-up version of the override folder. You should never need to place any edited files outside the override folder because anything that can be overridden will be checked for in the override folder. The only exceptions to this are when u are making MODs and want to have your own special version of dialog.tlk and/or chitin.key etc.
If u're not sure about something-try it out and if the worst happens (which let's face it is not very bad unless u are very very stupid in which case u won't be trying this stuff anyway

), just reinstall the game. However as I said, this shouldn't really be necessary if u make proper backups and try to edit only 1 or 2 things at a time and it certainly won't happen with basic item, spell and kit editing and most other editing.
Any other questions, I can try and answer, although I am just another experimenter like everyone else, so go easy on me.