How to tune basic turbo diesel engine?

Since diesals do not have spark plugs the ignition timing is done by the injection pump. If the pump timeing is off this is a sign of a major wear or broken gears.
--- The valves do need periodic adjustment but each vehical will have its own service procedure. This is also a complex task.
---Fuel filtration is important so change the filter and water seperator often. Fuel leaks can suck air in and be big HP loss.
---If by "tune" you mean make more horse power. You can turn up the fuel pump and install larger fuel injectors on some motors. Modify the waste gate on the turbo boosts HP at high RPM but makes the turbo spool up slower. Messing with the size of turbo also increases turbo lag or turbo boost pressure. For performance an intercooler is a must. Boost pressures above 50 PSI blow head gaskets unless you have O-ring head gaskets installed. I've seen etheline injection installed in the intake manifold but question if it works or will destroy the motor.
---Then if you up the horsepower the tranny and drive train will need adjusted to not blow.