A couple of questions:
1. Are you recruiting for a specific war? Historical or current?
2. Does it HAVE to be men you're recruiting? If it's for WWI or later, consider recruiting women in your poem -- it would be a bit different.
Taking that into consideration, consider structuring your poem like this:
1st Stanza: Why is America in this war? In other words, what are we fighting for?
2nd Stanza: Why should YOU join?
3rd Stanza: Describe the experience of a soldier.
4th Stanza: Talk about coming home a hero after the war is over.
And finally, here's a rhyming dictionary to help you out!
http://www.rhymezone.com/