First step, is to identify your highway, either you'll have one extending through your zone or, or if you just have an off/on ramp poking in, you'll plan to extend it across your whole zone. The key to your highway is to absolutely minimize intersections to it, it should only have 3-4 connections spaced across the whole map, two of these will be to your major avenues.
Step two is to start planning your road spacing. If you want an optimial grid, you won't be able to eye-ball it. Instead start at one edge of your map, and use small segments of dirt road and the built-in grid system to start determining the correct spacing.
Next up is to determine the location, of your main avenues, These are the primary roads that are going to connect back to your highway. I suggest placing them 4 blocks from the perimeter of the city. Unlike the smaller roads, you can't rely on the built-in grids to space the avenues, as they give too much room. Instead, you need to eyeball it at first, then test your spacing with the zoning tool to ensure it's one block width away from the dirt roads you placed.
Next up is to use the same technique to determine the grid spacing going in the other direction, this is going to be your first local street and it will prevent the other local streets from actually reaching the highway.
So these two shots illustrate the central concept of the guide which is that smaller streets run parallel to larger streets in order to minimize intersections and keep traffic flowing quickly.
This layout gradually expands across the whole map as the game progresses, you can avoid dead ends with temporary streets that you delete later, but I've found sims are pretty tolerant to long dead end streets so it shouldn't cause too much grief.