I'm building a 'simple' rocket engine with my classmates. It's fueled by liquid kerosene and gaseous oxygen. We have two valves in sequence on both lines, for controlling the startup of the engine. They are actuated by pressurized nitrogen gas, and the fuel tank is also pressurized by nitrogen. The pressure pushes fuel and oxygen into the combustion chamber through an injector plate. We have two more small valves at the fuel tank so that we can safely vent its pressure when needed.
At various points along the plumbing are pressure sensors, and around the engine are temperature and force sensors, all connected to computers on the test stand and in the control room. It's a fair amount of work to get all that integrated and tested to get the equipment working properly and the proper procedure developed before we will be able to ignite the engine for the first time.
Using a more energetic oxidizer like liquid oxygen will require the ability to fill the rocket tanks remotely, different materials, and more valves to make sure we can purge the lines safely.