There is a ton of info right here if your willing to dig for it and by that I mean use the search function. Look under phil hernon workout or Doggcrapp. There is no "right way" to train and many variables to consider. Mainly it comes down to diet. Do you eat enough of the right nutrients to ensure that you recover fully from each workout before you bomb the same body part again?
Simple as that! Some benifit from a routine similar to yours...training each body part one time per week, others twice per week. It's a "find what works best for you" kind of thing and the only way your going to find out is through experimenting with various routines. Many people here prefer the HIT style of training...I know I do/did. The diet is what will make or break you when it comes to adding lean muscle mass over time. This means an endless routine of cooking, packaging, freezing, cleaning and most of all...chewing/swallowing.
If you can organize your life around your meals and be consistent at it, there is no way you can't add muscle mass to your frame...juiced or natural.
It all comes back to how much you want it and what your willing to sacrifice to get it...relationships, beers with the guys/ladies, "quality" time with the wife/kids, your health, hairline, testicles etc. etc.
OK, i'm gonna shut up now. I believe xcell has summed it up in his signiture quite succinctly, 60% nutrition, 25% training, 10% rest, and 5% supplements.