There's plenty of regular maintenance to do on a motorcycle, much like with a car. One big difference if you have a chain driven motorcycle is to keep your drive train maintained through periodic inspection, lubing, adjusting, and replacing wear parts. Of course the owner's manual will have a comprehensive overview of the maintenance schedule. Here's an example from a 2012 Kawasaki Ninja (pdf document). This particular bike recommends changing oil once a year or once every 7500 miles once it is broken in, whichever comes first. I'd think if you were changing your oil yearly that you'd want to do so before the riding season begins, though I'd be interested to hear what other folks do.
In my experience, my 250 cc motorcycle gets about 60 mpg in regular city riding. For a single occupancy vehicle, this is certainly more efficient than a small car and competitive with the best hybrid cars. Bigger motorcycles get lower gas mileage, but they still tend to be comparable to small cars. As a rider, it is certainly my opinion that more of us should be considering motorycles over cars for single occupancy vehicles, though I may be a bit biased.