After buying a new stone edge polishing pads, steep it in a bath of lubricant and leave it until it absorbs no more oil. And always keep it moist when not in use.

An oilstone won't produce a true edge unless it is flat: avoid localized wear by using the whole surface of the stone, even when you are sharpening narrow bladed tools.

To check whether your stone is flat, lay a steel rule along, then across it. If you see any hollows it needs regrinding or replacing.

To regrind it you need a thick sheet of flat glass - an old car side screen from a breaker's yard is fine - and some carborundum powder. Lay the glass flat and spread it with a paste of the powder and water.

Rub the stone around, checking the stone tool surface frequently. Continue until the paste clings evenly to the whole surface, and then check again with the steel rule.

To maintain the stone in good order, it's best to keep it in a wooden oilstone box. This will stop dust from contaminating the surface and prevent it from being chipped.