Depending on how much you want to pay, untreated oil is likely fine? I suspect a light wipe with an oiled rag, keeping it clean and dry, and checking on it regularly, would work pretty well… oh, and storage. It’s far to easy to pack stuff away damp and find something horrible has happened months later.
And as for “okay for a first timer”… frankly, if you turn up in steel plate, you’ll be doing newbie armour brilliantly anyway
