I went to Japan twice pre-smartphone (with guidebooks) and once renting an iPhone 4:

1) In Tokyo, I found people tend to help more when approached. Even if their English is poor, they will usually make some effort to help. Outside Tokyo (even in other big cities), people tend to be more proactively helpful if they can tell you are confused/lost. In more than one instance, I've had people walk me part or all the way to my destination, sometimes even going out of their way on mass transit to help! This happened to my parents last month as well, so it wasn't a fluke.

2) One thing that is cool about Google Maps Street View is that you can even "move" along many streets, click by click. So you not only see your destination, but you could potentially see your entire route. This sounds a bit crazy, but it was tremendously helpful in my last trip when I couldn't use my phone or carry a map for religious reasons and still knew exactly how to get to my destination from the hotel and what to look for on the way.

3) If you are anxious about getting lost, one thing that relaxes me in Tokyo (or any city with a well marked subway system) is that as long I can get to a station, I can find my way back to the hotel. Tokyo's is more extensive and confusing than most other systems, but if you know the subway line and station closest to your hotel, you can certainly ask at the station how to get back. This, combined with the aforementioned general safety and friendliness/helpfulness should ease your anxiety.