I'd have him start with the obvious...
- Clean and gap the sparkplug
- Clean the air filter, or replace it
- Change oil
There is no starting choke on these things. There are instructions in the manual that came with it for these things. The air cleaner comes off with a screwdriver usually. They are a "dry" type, and can't be cleaned, so just replace, typically, once a season.
Oil should be 10W30. Likely a quart or less. Wrench (socket) usually, to take out fitting. Don't overfill.
Sparkplug will need a sparkplug wrench. I would suggest he replace it annually anyways. Put some "anti seize" on the threads, and don't overtighten. Anti-seize (from any good auto supply store) lets you take the sucker apart in the future with much greater ease!
While he is at it, take off the blade (pull the sparkplug wire off first!!!). Socket wrench needed here. File ALONG the blade to take out any nicks, and put a better edge on it. Maintain the contour of the old blade. Do not take off excessive metal, or you can get it out of balance.
These things should be done once a season, as a rule. If I am using my mower heavily, then I will change about every 20 hours of usage. Also, oil or grease the wheel bearings, as appropriate. A small grease gun might be needed. Use a heavy oil for the wheel bearings, if they aren't the grease kind.
Blow out the crap/dead grass/etc. from the air ducts. Stuff there can cause things to easily overheat.
All the stuff you need can be obtained at any "big box" store, or your local hardware store.
If there is a drive belt, check its condition. Keep a spare around, along with a spare plug, and spare air filter. The number for the plug size is on the insulator of the plug.
Hose the mower off now and then, and especially underneath where grass builds up. This is especially an issue with the "mulching" mowers.
Sunburn and blisters are on your own...