A few more example sounds from Ghost to try out and have fun with. Open them up in Audacity to get an idea of how they should sound and also to see appropriate levels for each.
http://www.mediafire.com/download/e5w985mp56q08n4/st6_us_examples.zip
Some tips to help recording:
Record for one minute with a higher gain but dont say anything. Use it to see what ambient sounds it picks up and see if you can find the sources and eliminate them.
Computers are the worst especially with fan noises. Maybe cover temporarily with a towel while recording. All unneeded electronic devices in general should be turned off.
Keep the mic 2-3 inches away from the mouth. If this isnt possible, such as a headset, remove the set and hold it slightly away. Keep back from walls and corners to avoid reverb. If the cord is long enough stand away from the computer. Adjust the gain so the sound is not muddled nor does it blow out the mic.
Record it all in one long stream and not a bunch of little ones. Have a sheet a paper with all the lines. Start the recording. Speak into the mic using different variations on the dialog and what you like. Experiment and feel free to improvise.
Last but not least, anyone can read lines. Remember that you are actors maties.
edit: And in case anyone asks, a good male/female mixture would be great. It doesnt have to be a male Marine that says "Enemy AC130 inbound".