If you are nervous about opening doors on the actual model, then I suggest getting a cheap model and practice on that one. This way you will get the feel of opening doors and if you make a mistake all you would lose is time and perhaps the practice model. Never ever use your actual model as a so-called testbed!
Also, the smart thing to do along with using a scrape model is follow Mr. Obsessives advice. If there is one guy who knows how things are to be done, it is Mr. Obsessive.