All I can really say is that you've chosen a pretty big challenge for your first Poser project. Odds are in the favor of you choking on it, I'm afraid. I hope I'm wrong, but that's how I feel.
Honestly, start slow. Doing big projects when you're learning will usually result in big projects you want to redo when you're more experienced. Four eras with clothes and stuff is a lot to handle and I strongly suggest you to consider doing smaller projects first. I know I wouldn't touch a 4 era Khmer leaderhead before becoming a lot better with Poser.
As for the preview, the head is ok, but there isn't much else to criticize. Background isn't in my opinion good - confusing and not in key with other leaderhead backgrounds.