Assuming your goal is to keep it and not sell it, the first thing I would do is change the oil in the engine and generator. You don't need a "tune up" on the 2009.
Second thing I would do depends on how full the fuel tank is. If it's close to full, I'd drain and refill it and then replace the fuel filter after 500 miles. If it's closer to empty, I would probably put some fuel conditioner in the tank and fill it with premium. Then replace the fuel filter after 500 miles.
Third thing I would do is keep an eye out for a tire sale. They will need to be replaced sooner rather than later.
After that, I'd probably start driving it for short trips (errands around town) and see how things go. Work up to short overnight trips. It's not worth (IMO) replacing a lot of parts that might be fine.
You don't need a full plan before you start. Take care of the most important items and see how things progress.