1. Like above, port forward your router to 25565. This is to make sure people can actually connect to your server properly.
2. Go into command prompt, type "java -version" If you get "'Java' is not recognized as an internal or external command, operable program or batch file.", then you have a version less than 1.6 and you need to update to very latest version. Depends on what bit architecture you are using. 32bit java obviously for 32 bit windows.
3. Does your computer's Video graphics card use SSE4? If so, nice things can be done. What amount of RAM do you have for use? 2GB RAM at least. (This is in regards to memory usage of your server, which will be dreadful without a decent command-line start-up bat file)
4. When you download one of the modpacks, you may notice they do not start with a few average server files that a minecraft server generally needs. Things like banned-players.txt and server.properties will not be in the zip file. Grab those from the .jar from the normal minecraft server download off minecraft.net. You will be needing those. (Those refers to "banned-players.txt, banned-ips.txt, ops.txt, server.properties and whitelist.txt")
5. Step by step? I hope I listed most of the things. I recommend running a whitelisted server, if you are running one simply for friends and friends alone. This allows you to manage the amount of players on your server.
6. Feed the Beast is quite the whopper compared to a regular server, it has different needs. Make backup's of your server at least once a week mate.
7. Tell me I've missed something. I'm sure I've missed something.
Most of these things can be found out about either on
http://www.minecraftwiki.net/wiki/Tutorials/Setting_up_a_server#Port_forwarding
or
simply youtube/google
Feel free to ask more questions. I probably won't be able to get back to you soon, but someone else might/will.