Get some 2 x 4 twice the length of the deck's width.
put them under the deck then lower onto them
Unclip the pins, should be around 6.
2 each side near the rear then 1 or 2 at the front and perhaps a stabilizer across the very back.
Slide the deck a little forward to get enough slack to slip the belt of the engine pulley then slide the deck out sideways on the 2 x 4' s like rails.
Blow the deck down and spray every part that moves with dry lithium grease.
Get under the mower & have some one move all of the controls ans spray everywhere that 2 metal parts move in each other, do not be shy.
Don't forget the height adjusters on the rear guard, I generally pull the back wheels off and lube the axels which makes the rear bits easy to access.
To get an idea, I go through a large can of grease every 2 or 3 mowers.
Don't forget all the pins you just pulled out.
Jack the front off the ground and grease the nipples in the steering & wheels.
Very important to have the wheels hanging free so the grease gets between the faces that are normally bearing on each other.
Some front cross beams have a nipple in the middle where they pivot, some don't.
If you have a pressed metal front cross beam then spray the flange it pivots on front & back, again you can't get too much in there.
FWIW takes me a bit over an hour to do it properly so allow yourself 2 hours.
If you have a compressor get a long dust gun, longer the better and blow the underside clean before you start, no use lubing dust & debris.
When you have finished, slide the deck back in on the 2 x 4's and hook it up, starting at the back & finishing with the drag links at the front.
On the subject f drag links, most mowers do not have tie rod ends any more ( add too much cost ) so slip the extension tube of the spray grease under the rubber skirt, if fitted ad give them a good squirt as well.
If you have open ball joints then give the balls a spray .
While the deck is out, spin the blades & check the shafts for any up down or side to side movement and for smoothness of rotation, if they are bad replace the bearings.
Also spin any idler pulleys checking for a smooth quiet spin, if not replace them as well, a lot cheaper & easier now and it won't cost a new belt 1/2 way through doing the lawn just before the in laws turn up for their annual inspection.
When you are under the mower set the brake then do the same for the pulleys in the drive train ( 3 usually ).
Slide the belt through 1 full revolution & check for cracks, shredding , missing lumps etc.
Now run the engine , change the oil & filters then remove the blower housing & blow clean the cooling fins.
Leave the blower housing off over winter to discourage it becoming the rodent Hilton over winter.
Drain the fuel or add your favourite stabilizer & the mower is set for a winters snooze.
I you have a battery tender, hook it up or try to remember to pop the charger onto the battery overnight once a month.