I'm currently using FastCGI to implement part of our web application, mainly since mod_perl was not available on our first web host. We're planning to phase out the FastCGI scripts in favor of mod_perl very soon, however.
About the only tips I can offer are:
- Use the CGI::Fast module. It nicely takes care of some little quirks of FastCGI and provides a clean interface to CGI.pm.
- Be very sure to re-initialize all of your variables for every request. This is the same problem that many people have ben coding for mod_perl -- FastCGI scripts, like mod_perl scripts, are persistant, so modified variables may end up hanging around longer than you want them to.