Ceres is the extreme example of the Grineer's utilitarian ignorance of the natural landscape. Their expanding shipyard operations pollute and shroud the planet in smog and industrial waste as they manufacture machines of war. These foundries are scattered across the Solar System, giving them near-limitless reach with their fleets.
Most missions on Ceres take place in the Grineer Shipyard tile set, which was first featured in the Tethra's Doom event and then implemented permanently in Update 13.0. Ceres was also the first planet to have Hijack missions available, introduced in the same event.
Kiste, Cinxia, Casta, and Draco are excellent missions to look for Orokin Cells.
The Seimeni and Gabii Dark Sectors are a great place to farm credits, offering 12,400 12,400 per mission provided players are in a fully-occupied Cell.
Particularly if you are playing alone, make sure that you have all four base elements (Cold, Electricity, Heat, and Toxin) on your weapons, as Prosecutor Guardsmen enemy types are only vulnerable to one specific element.
Try to build towards having one base element on your primary weapon, one on your secondary weapon, another on your melee weapon, and a final base element on your sentinel weapon.
Ceres is the only known dwarf planet in the inner solar system and the closest of the five identified dwarf planets recognized by the IAU, and may have liquid water. This may the source of the constant rainstorms that occur on the shipyards, which may be a product of the Grineer's shipbuilding operations.
Ceres is a very interesting and strategic point for the Grineer. As the dwarf planet is located in the Asteroid Belt (and is the only dwarf planet located there), the Grineer can easily mine the nearby bounty of mineral and metal-rich asteroids to build their ships.