I want to tune up my lawn mower ???

I guess it would depend on what type of lawn mower you have. Need more info. Dan.

You'll probably want to do several of the following, but check your owner's manual for what they recommend:

• clean / replace air filter
• clean / replace fuel filter
• replace spark plugs
• tighten all housing screws
• lubricate moving parts such as the deadman clutch line
• thoroughly clean inside of mower pan
• remove, sharpen and balance mower blade

Some of these are every use, like cleaning the pan, others are every N hours of use, others are once a season. Also, you'll want to correctly store the mower for the winter. And safe mower maintenance includes unplugging the spark plug, so it can't start accidentally.

realy just change oil and clean air filter if dirty and follow your manual

dont take it to a shop. heres a good mower site. in particular drain the fuel each year and make sure it has oil.

listen to your friend if you want it to preserve it and it stays in top condition.... if you have to ask a question like this then you dont know how to do the tuneup and will only mess it up.

Drain gas. Change oil. Put some ND-30 in the cylinder. Pull motor cover, and clean out any dust or dirt.

If you don't know how to do all this, take it to the shop.

Your owner's manual will tell you what should be done. Keeping the blade sharp, replacing worn parts, using fresh clean gasoline, and changing the oil, and changing/cleaning the filters are all important.