Your best bet is appropriate medical treatment to control symptoms. Aside from that, just like everyone else, you should consider a solid tripod. You can also lean against solid objects (trees, walls) to increase your stability.
The tremor in Parkinson Disease is a resting tremor. When you are actively using your muscles, tremor should be absent. Other symptoms include rigidity, bradykinesia (inability to move quickly), micrographia (tiny writing), reduced balance and coordination, tendency to lean forward (and fall over) when walking.
If you have early-onset Parkinson Disease, bradykinesia and rigidity are likely of greater significance than tremors. These could result in both peripheral (arms and legs) and central (core body) instability.
Consequently, the following are unlikely to be helpful:
- Solutions that primarily address tremor (because tremor is not the primary problem).
- Solutions that depend on core stability, such as monopods and body braces.
- Solutions that require carrying rigs around (because of poor balance, coordination, and core stability).
If you have something resembling essential tremor, rather than resting tremor, you may benefit from consulting your neurologist for further explanation. Note that Parkinsonism is distinct from Parkinson Disease, and there are many conditions that can present similarly.