We have found that Craigslist is your best option for a rental. 85% to 95% of all rentals leased in San Diego County are found using Craigslist. It is used to advertise rentals by property owners, property management companies and agents alike.
Start by putting your preferred zip code in the search box and then enter the rest of your requirements, including the check boxes for pets if needed. There is also a pull down menu for the type of property you are seeking (apartment, house, etc) Check often and call/e-mail right away as many rentals move quickly.
Beware of rental scam listings and ads that "look too good to be true”. Make sure you talk to the person managing the property and meet them to see it. Scams usually involve people asking for a deposit in order to see the property. The "owner" usually states they live out of state or out of the country. Other scams involve people stealing pictures from homes for sale and then posting it as a rental with a low rental rate.
Best of luck to you,
Mark & Kari Shea
Shea Real Estate
National Association of Realtors
CA BRE License 01713506