How to overcome fear of user-input (web development)

Question

I'm writing a web application for public consumption...How do you get over/ deal with the fear of User Input? As a web developer, you know the tricks and holes that exist that can be exploited particularly on the web which are made all the more easier with add-ons like Firebug etc

Sometimes it's so overwhelming you just want to forget the whole deal (does make you appreciate Intranet Development though!)

Sorry if this isn't a question that can be answered simply, but perhaps ideas or strategies that are helpful...Thanks!

Answer 1

One word: server-side validation (ok, that may have been three words).