1. First and most vital - Defend at Galv. Nothing, I repeat; NOTHING screws the alliance more in AV than breaking their zerg and Galvangar is the single best place to do this.
2. Hold Galv and Tower Point and recap any towers that may have been ninja'd, particularly IBT. Rogues at this point should proceed north in pairs to take mines and ninja towers disrupting Alliance further from breaking the chokehold at Galv and Tower Point. When all (or most if one was somehow lost) Horde Towers are secured (ie. not in immediate danger) advance on Balinda but have the Galv team remain to protect Galvangar for as long as is humanely possible.
Once Balinda goes down it's up to you and how smoothly things went up to that point where to go from there. Once Galv is lost, the team defending him should proceed north immediately and assist in taking down the enemy towers. If Balinda went down first most likely you've already won.
Horde naturally have the terrain disadvantage in AV from having to proceed uphill but breaking the Alliance Zerg at Galv (thus forcing them to reorganize which we all know is the easiest thing in the world to do in a PuG) greatly levels the playing field for us.
Edit: A point I forgot but others have duly covered, DO NOT TAKE SNOWFALL. And importantly remind the group (for the sake of the new players) not to take snowfall.
That said if you're gunning for the Grave Robber achievement for the meta Snowfall is actually one of the best places to grab for an easy point since it's so out of the way and your only competition will probably be a newbie anyway if any at all (screw your team; battlemaster awaits?)