Security
Easy access to information is what FileMaker's all about. But that's a double-edged sword. As it stands now, every person who uses your database has unrestricted access. Of course, you can take all the usual precautions (give your computer a password, install virus protection software, lock your door, and so on). But eventually, you'll probably want to let other people work in your database, and that brings up all kinds of security challenges. Mike in Accounting is free to rename all your scripts if he so desires. And Kelly in Sales can delete all those "old" order records that are getting in her way. Fortunately, FileMaker has features of its own that give you a finer level of control, so you can let selected people use your database to the fullest, while keeping important information out of harm's way.
You may be tempted to think you don't have to worry about security. But the best time to think about protecting your data is before you have a problem. If you wait until your database grows big and complex before considering security, it'll take you longer to build in later.