Do NOT leave ANY valuables in your vehicle when parking at any trail head parking lot (Hole in the fence at Morris Bridge riding area is a good example, Boyette Scrub Preserve is another) . Bring your wallet with you on the bike or leave it at home and just bring your Driver's License.
Do not leave any cases, bags or "important" looking packages in plain view of your windows, use the trunk or put things behind and under the back of your seats. This includes brief cases, gear bags and bundles of clothes. Leave nothing in plain site.
Do keep a list of important phone numbers handy where you can quickly report any/all stolen credit cards. Locally, CC's can be used 4 times or more within 60 minutes of being stolen.
Watch out for, and report, suspicious activity in and around ANY trail head parking area, no matter what park you are in. Look for smashed windows or key locks with bigger than normal holes. Don't confront anyone though. Remember that all parks are outside of city limits and are under the jurisdiction of the local sheriff. Notify park rangers of any activity and note that the rangers can't be everywhere nor can they watch everything. Write down a description of vehicles, people and license plates for people that do not look like they belong. (Just don't mistake runners and hikers for this group). The plates might be stolen on that suspicious car but even that is good information for investigators.
Key reason for this e-mail message: Do not let kids stealing gas money ruin your week.
Most importantly, once you and your belongings are safe, relax and have a great time on the trails.