The most important guide any tourist requires is a proper and clear map.
But the question comes to my mind is how one can start making their own maps so that he will always have this in reference for next trip...
It would be far more efficient to modify existing maps if anything on them has changed, or if you want to add personal notes to them.
Back in the day when I was delivering pizza, I had a map of the town with frequent customers' houses marked, and a few updates and shortcuts drawn in.
Collect tourist, transit or road maps at the local tourist centre... or give the local or state/provincial tourist authority and request maps.
You can add your own notes on the maps.
Use google maps, zoom in, knob "Print Screen" and paste the now taken picture into a picture program like Paint Shop Pro. Cut the a square part out without text and sliders. Then do the same for an adjacent area and so on. In the end you have made a pretty delailed map.
Yes, there is no need to reinvent the wheel. Google Maps or Google earth are a good starting point and both offer an API (application programming interface) which basically lets you add stuff (icons, pictures, info, etc.) "on top" of the map.