I winterized my boat before winter storage for the first time and I took pictures and noted the steps. The motor is a 140HP Suzuki 4-Stroke. I stopped into a local boat dealer to pick up the materials and get some direction. The steps are listed below.

Materials:

1.  Gas treatment
2. Oil (4 stroke synthetic blend)
3. Lower unit grease
4. Oil filter
5. Water hose & motor ear muffs (if needed....most new motors have a built-in hose connector) 

Step #1:

Hook up ear muffs to motor and turn on water

Step #2

Add the gas treatment to the a gallon of gas in a seperate can.

Step #3

Start the motor and let the treatment run through until the motor quits. Took around 20 minutes.  Turn off water.

Step #4

Drain motor oil from side casing

Step #5

Remove oil filter

Step #6

Replace filter and add new oil

Step #7

Drain lower unit grease

Step #8

Use lower unit grease pump to pump in new lower unit grease

Step #9

Remove cotter pin from prop shaft and remove prop to grease the prop shaft

Step #10

Last thing.....grease the wheels of your trailer

Not bad for my first time doing it. It took a bit of time to find some of the screws on the motor to remove to get to the oil filter and some other things took a bit to figure out, but now that I have done it once, it should be a breeze next time. Should be able to cut if from a couple hours to no longer than an hour next time.