Using just your first name can also be a good option, if it's unique. But:
# Beware that IRC "seems" case-sensitive but actually isn't: e.g. <tt>/whois mossop</tt> (all lowercase) will return info on Mossop (with initial capital) if he's online, and <tt>/nick mossop</tt> will either be refused (if Mossop is online) or make NickServ tell you that this nick is registered and that you should IDENTIFY with its password if it's yours (if he isn't). ([[#Register your nickname|See below]] about this NickServ stuff.)
If you are new to IRC and you use a female name you will most likely at some point get private messages from people that are unwelcome. This is hopefully less frequent on the Mozilla network but this behaviour does exist anywhere that also allows anonymity so take this into consideration in choosing your nickname and make sure you are prepared to fend off jerks.
====Set your nickname====