The official guidebooks are the best source of information on parking. Some official maps also indicate parking. Shuttle providers are often excellent sources. Hiker comments can be found at the Appalachian Trail Parking in PA web site . We can never guarantee the safety of any location.
Remote trailheads tend to have the greatest risk.
To help foster good will toward the hiking community, consider offering to pay a few dollars for each night you leave your car. Businesses close to the Trail are listed in The Appalachian Trail Thru-Hikers' Companion. Never leave valuables in sight. The best place to stow them is in the trunk. Bake Oven Knob Rd.