It's been a while for me, but I have done a lot of nugget shooting in Plumas and Sierra counties. I don't know what your budget is, but for the average guy, good gold machines take a pretty hefty bite outta their savings when they're first starting out (did me). That said, you definitely want a quality machine. If money is a limiting factor, don't buy a cheap, low-quality new one–with the same money, buy a good-quality used one. They are aren't hard to find, and they're a whole lot more efficient, dependable, and cheaper. When I got into nugget shooting, I had success with an old Whites CoinMaster (1985), then upgraded to the Fisher Gold Bug, then the Minelab Eureka Gold, and Minelab GPX-4000. Of course, the CoinMaster is a real dinosaur and not recommended for nugget shooting. But the others are all excellent gold getters. I don't think you can go wrong with any of them. The Gold Bug really served me well, used the hell outta it, and though I didn't treat it gently, it always was ready for duty, fully operational, and never complained. There are others too that are just as well-liked by gold prospectors, however, the ones I mentioned are the machines I've used and that I can recommend highly from personal experience.
You've picked some good gold country to hunt--great scenery, excellent camping, good gold throughout the area. Good luck!