- last post: 01.01.0001 12:00 AM PDT
Open ports 2302-2305 on your router, for starters.
Check the obvious settings; make sure your game isn't password encrypted, that it isn't a PC mod (cause sometimes they don't show up), etc.
Next, check for firewalls, they hinder people from joining. ZoneAlarm's trial version, for example has a known incompat issue with halopc. Each firewall is different; for some, you may need to merely allow halo, while for other firewalls you may need to shut it down completely. And the bulit-in WindowsXP firewall doesn't stop Halo.
Finally, get Xfire and a few buddies together. Xfire is an instant messaging system that works with halo, not against it. It allows you to IM each other while in game, but it's usefulness in this case comes in with it's "direcconect" feature. This allows your friends to jump into your game. So, once Xfire is running, fire up your server, then ping your buddies to join you. If they can join, you're good to go. If they can't, you'll know they can't because they'll ping you back.
EDIT: I almost forgot, sometimes, people simply won't join your server for whatever reason. There are really fast days, and really slow days. As long as your game name isn't discriminating or something, but big and friendly, say "All Are Welcome...please join!", then you should get some players eventually.
[Edited on 11/16/2005]