simple relay circuit - improvements?

Hi All, I’ve been working on a simple relay circuit. I’ve attached a block diagram I did in google draw. I’ve built the circuit and it works. I drew it afterwards by looking at my (ghastly) prototype board I soldered up, so hopefully I got it right! So what I am wondering is, am I missing anything essential like a capacitor to smooth things out, or something else to promote longevity of the components. The arduino and 12V supply are coming from wallwart transformers.

My understanding of this circuit is:
arduino triggers the npn which triggers the relay which controls “current”
the diode is there for flyback protection
the led is just and indicator for when the relay switch is closed

Basically, does this circuit need to be improved?
Can it be replicated on a single board?
Other considerations?

thanks!

relayBlockDiagram.pdf (29.6 KB)

Diagram looks good.
May be look for a free schematic dawning program.
Anode of LED towards +V, cathode of diode towards +V, collector towards +V and emitter to 0V.
Some relays are polarity sensitive.
Observer current rating of the relay contacts, if driving an inductive load you may need arc suppression (capacitor/resistor)
For long distances opto coupler may be advised to reduce noise pickup on the Arduino.

Can it be replicated on a single board? Yes, of course.