http://www.youtube.com/watch?v=ztQD4V-gpxY&feature=relatedThis is one of the best I find, but it's not perfect tutorial. Use grid to place roads in a line (at least while you practice and in a zone where you'll place lots) so you don't have to move roads too much. Also you can see the dark blue square at the end of the road that you are placing/moving, well, if you click and drag that square you can move and stretch or extend your road. Green squares are for curves on the road. Each time you place road square, you want it to be connected well or in game play your Sim will exit car and walk over each road square.
Also, I find it easier to plan ahead, and place lot for large central park (or whatever you want, like plaza, shopping area whatever), and then line roads around it. And do parts of the map like that, rather than do all roads at once. It is not hard once you learn tricks, but first couple of attempts are the hardest. I spent 2 hours placing my first bridge in a perfect line, now I can do it in a few minutes, it all comes together eventually.
