Just a few cost effective travel tips when traveling to Tijuana:
When arriving at San Diego International Airport you can catch the 992 bus and connect to the Downtown Trolley Station at America Plaza. Then catch the Blue Line Trolley to the San Ysidro Border. $2.50 each way.
If you have a car you can park for 24 hours free at the Palm Avenue Trolley Station and then catchthe Blue Line Trolley 2 stops to the border. The parking lot has many security cameras onsite. There is also street parking for extended days.
These are some options compared to parking at the border in San Ysidro with the inflated parking rates, especially during the weekend when prices are at a premium.
Once you cross the border, walk down to the turnstiles where the taxis are. Just to the left of the taxis you can order Uber where the passenger vans are. Uber is usually $2-$3USD to Zona Norte.