Don't start tor right away when launching TBB the first time
Right now (OS X), after downloading the Tor Browser Bundle, it tries to start up Tor immediately upon first run.
There should be a dialog querying users whether they want to alter settings first, as a bare start of Tor (rather than allowing them to e.g. click 'my ISP blocks connections to the Tor network' and add obfsproxy bridges) could immediately unmask the user on networks where censors attempt to detect and/or identify Tor users.
Trac:
Username: gmorehouse