Up/down - as simple as that, right?
I agree with the above. However, I would like to add some further risk considerations.
Most pilots in your position are puzzled by the "fancy" propellor, but expects that handling the undercarriage is as simple as switching on and off the landing light.
Actually, it is the other way around. Handling the propellor is fairly simple and close to idiot proof - if in doubt, push the lever forward and go to high RPM. Propellor governor failures are rare and don't usually cause accidents.
The retractable undercarriage, on the other hand, is responsible for most of the trouble. This is only partly due to the obvious possibility of a wheels-up landing. Another more serious risk factor is that a complex airplane with the undercarriage retracted is slippier that the fixed gear version, and if the pilot loses control, it will accelerate towards Vne much quicker. For this reason accident rates due to loss of control are higher with complex aeroplanes.
So, if you ever lose control at altitude in a complex aircraft, it is probably the best option to extend the gear immediately, even if you are above the gear extension limit speed.
Gear-up landings are embarassing if caused by a distraction or by lack of familiarity with aircraft systems. But usually the damage is limited to the pilot's ego and a little to the aircraft's underside. Two exceptions:
1) Gear-up landing on grass. Unlike on hard surfaces, there is a risk that the aircraft will turn over on its back, which sometimes is critical. Always land on a hard surface if you suspect or know of gear problems.
2) Ultra-low go-around with gear retracted. Sometimes the airplane is down in the landing flare, before the pilot realizes that the gear is still retracted. If the pilot then throttles up and goes around, there is a risk of prop strike. It has happened more than once, that an aircraft climbing to circuit altitude has experiences prop blade failure after an undetected prop strike with the gear retracted. Such failures are usually serious, occasionally fatal.
So make sure you understand the gear system of any retractable aircraft you fly. To power gear retraction Cessnas have an electro-hyd-pack that is known to have failures, especially if not expertly maintained. The pack is able to drain the battery in a short time if the pump is left running e.g. due to pressure switch failure or a fluid leak.
I don't mean to scare anyone away. I find retractable Cessnas (and many other retractables) a delight to fly (177RG is my favorite). Just don't let the gear - or its implications - take you by surprise.