If you own one lure, own this one.
A spinner is a bent wire, a weight and a blade that turns. It sends out flash and vibration on a plain straight retrieve, which means it catches fish while you are still learning where they are and how the rod feels — the two things that actually take time.
Blade shape is the only decision
Colorado blades are round, spin wide, thump hard and run shallow. They are the choice in coloured water, over weed beds, and any time the fish need to find the lure by feel.
Willow blades are long and narrow, spin tight, flash more and run faster and deeper. Clear water, brighter days, more active fish.
Buy both, in silver and gold. That is four combinations and it covers nearly everything.
Buy several of the same one
You will lose lures. Specifically, you will lose them on the sunken log, the weed edge and the rocky point — which are exactly the places worth casting to. An angler with one expensive lure fishes timidly and catches nothing; an angler with six cheap ones fishes the structure and catches fish.
When this is the wrong lure
If the fish are holding deep — on a drop-off, in summer, in a deep pool — a spinner run over the top of them is not a subtle failure, it is a complete one. That is what a diving lure is for, and no amount of good technique substitutes for being at the right depth.