Using *hi* is a bad idea for a trigger because "hi" can be in a LOT of different words. At the very least, you would want to use hi* instead of *hi* because that at least requires that the line/word starts with "hi" so it doesn't trigger on something like "this is fun."
Beyond that, there are various ways you can limit the script so that it is less likely to respond to the wrong thing. It just depends what you're doing and how you want it to work.
