To clean it first start with a cool engine. If your mower has a fuel valve switch it off. If you can disconnect the spark plug too. Next use a leaf blower to blast away any old dirt and major debris. Now gently lay the mower on its side fuel cap facing up. Try to get rid of any junk on the mowers underside as well.
Top 5 Lawn Mowers recommends the Sun Joe MJ401E to people with a small yard who dont want to spend a lot on a mower. The reviewer liked it overall for many of the same reason one might like any electric mower (no fossil fuels lightweight etc.) but he also noted that there were only three height positions with the lowest scraping the ground. And due to its 14-inch blade it takes longer to mow a lawn.
Gather what you need First gather your tools and equipment. You will need a power drill eye protection work gloves and a blade sharpening kit. The kit should come with a ceramic blade sharpener and balancer. Expect to pay about $8 for the kit at your local hardware store. You will also need a torque wrench (or a socket wrench in a pinch) and a wooden block. Consider having a rubber mallet on hand too.