To return to San Ysidro and Southern California, head north on Avenida Revolución and follow signs to San Diego. Avenida Padre Kino, north of the downtown area, is an alternative when traffic is heaviest. It connects you to the east lanes of the border crossing, which tend to be less crowded.
The 100-kilometer route from Tijuana [1] to Ensenada [2] is easy to follow. Most travelers these days take the four-lane toll road (Cuota), Mexico 1 D, south, but you can also choose the two-lane Libre (free road), which is the original Mexico 1. The toll road hugs the coast more closely but offers fewer opportunities for stops.
To get on the toll road from downtown Tijuana, get on Calle 3 heading west and look for signs to Ensenada; traffic may crawl until the toll-road entrance near Playas de Tijuana [3]. There are three tolls (casetas de cobro, US$2–3 each for regular passenger vehicles) along the way. You can pay in dollars or pesos, and your change may come in either currency depending on what the toll collector has on hand.
If you can manage to find it from downtown Tijuana, the Libre follows an inland route at first and meets the coast at Rosarito [4]. It then parallels the shore until La Misíon [5], where it heads into the mountains again. Access to the free road is not well marked downtown. Drive south along Avenida Revolución until it joins Boulevard Agua Caliente and watch for a sign that says A Rosarito (To Rosarito) and points right. Pass the Calimax store on the right and take the next right turn onto Boulevard Cuauhtémoc, which leads eventually to Mexico 1.
If you want to travel east on the Libre, take Boulevard Agua Caliente southeast. It will turn into Boulevard Díaz Ordaz and then Mexico 2. If you want to take the toll road to Tecate [6], follow the signs for the airport, not the signs for Tecate, which direct you toward the free road.
Links:
[1] http://www.moon.com/destinations/baja-cabo/tijuana-rosarito-and-tecate/tijuana
[2] http://www.moon.com/destinations/baja-cabo/ensenada-el-rosario/ensenada
[3] http://www.moon.com/destinations/baja-cabo/tijuana-rosarito-and-tecate/tijuana/sights
[4] http://www.moon.com/destinations/baja-cabo/tijuana-rosarito-and-tecate/rosarito
[5] http://www.moon.com/destinations/baja-cabo/tijuana-rosarito-and-tecate/south-rosarito/la-mision-and-la-fonda
[6] http://www.moon.com/destinations/baja-cabo/tijuana-rosarito-and-tecate/tecate