If you're a stickler for proper maintenance, you winterized your lawn mower when you put it into storage last fall. Unfortunately, few of us really are sticklers. So when spring rolls around we have to stone for our sins, or cope with a balky mower for the rest of the season. If you'd rather stone than cope, here's how.

Take your mower outside where you'll have plenty of light, ventilation and the freedom to spill a little oil. Then, before you do anything else, disconnect the spark plug wire. If there's a bare metal connector on the end of the wire, cover it with a few turns of electrician's tape. Now the mower is safe to work on.

If your mower has a four-cycle engine, drain the oil. On most mowers you do this by unscrewing a plug beneath the mower deck. Try to catch the old oil in a shallow pan, low enough to slide under the mower.

While the oil is draining into the pan, check over the gas tank. If it's not empty, you should get rid of the old gasoline that can gum up the engine. If there's a bit of gas left in the tank you can soak it up with a clean rag. Many of the newer plastic tanks will slide out of their mounts so you can just dump their contents into a can. Sometimes you'll have to drain the tank by disconnecting the fuel line leading to the carburetor. Disconnect it at the carb end and let it drain into a can. Be careful not to damage the hose if you use this method.

Once the tank is drained you can check the blade. But first, replace the oil drain plug so you won't get any dirt into the crankcase. Then tip the mower over on its side. If the blade looks sharp with no huge nicks, you can leave it alone. Otherwise remove it.

Jam the blade with a block of wood so it can't turn, and remove its mounting bolt. Note the orientation of the blade so you can replace it right-side up. (Note: If you forget which the way the blade goes, pull gently on the starter to see which way the blade shaft turns. Obviously the blade goes on sharp edge forward.)

You can sharpen a dull blade at home if you have a grinder or, better yet, a grinding attachment for a power drill, in which case you don't even have to remove the blade. Otherwise, it's simpler to buy a new blade. It will only cost a few bucks, and it's money well spent. A dull blade will stall and overstrain your engine. And chances are a badly nicked blade will be out of balance, a condition that can shake your mower to an early grave.

Whether you sharpen or buy a new blade, be sure to tighten up firmly on the mounting bolt when you put the blade in place. Again, use a block of wood to jam the blade while you wrench the bolt down tight.

Anothe small investment that makes a lot of sense is a new spark plug. Before you install it, check its gap with a feeler gauge. Even if you buy the right plug, that's no gaurantee it will have the right gap (printed in your owner's manual).

Now refill the crankcase with fresh oil of the type called for in your owner's manual.Fill the fuel tank with fresh gasoline, not leftovers from last season. Reconnect the spark plug wire and you should be ready for a season of easy starts and dependable performance.