You may pick your own username; however, since a username is representative of an organization's name, it is subject to policy 70.40 - Use of University Name of the Policies Applying to Campus Activities, Organizations, and Students. This means, usernames cannot begin with "uci" because although UCI recongizes campus organizations, they are not officially part of the University infrastructure in the same way an official department or program would be.
Check the UCI directory to make sure the username is not already in use by a member of the UCI community, i.e. faculty, staff, or student.
must be 3-32 alpha-numeric characters in length (4 or more characters preferred)
underscores or dashes may be used to separate words
Use of the account is bound to the terms of the UCI Computer and Network Use Policy, where applicable. For example, accounts cannot be used for commercial purposes, sending SPAM, harrassment, or other purposes which may be considered abuse or abusive. Furthermore, campus organizations are recognized by the University but do not officially represent UCI so they may not use official branding or wordmarks, and they are limited in the use of its name to indicate geographic location only. (See "username selection" above)