Getting all the nooks and crannies that are so common on tractors can be enough to drive ya nuts.
Solvent of choice, both in a spray bottle and a jar/pan/open top container.
Rags... lots of em.
Wire brush where you have rust or non painted surface you dont care about hurting the finish.
Old paint brush or softer bristle parts brush for painted surfaces.
Compressor and sprayer nozzle.
Safety glasses, other PPE. (Personal Protective Equipment)
Wipe off what you can, spray down with solvent, let it soak in, respray, losen with a brush, respray as needed, brush, wipe off what you can, repray, air hose out the corners/nooks/crannies, spray/wipe in what ever order you need to get as clean as you want. You'll likely get one area nicely cleaned up then knock the biggest off of the rest when you see how frustrating it can be...
Best of luck... post before and after pics!