The sun, being as bright as it is, makes the viewing of this event rather complicated. Although the transit of Mercury is visible to the naked eye, there will be about 7 and a half hours of almost complete sunlight involved, so that would be rather damaging were you to kick back and watch unprotected. The Weather Channel suggests setting up a solar projection box and observing the sun's light with a pinhole display, or using an aluminized solar filter on a telescope set towards the sun.
Interestingly enough, there are a couple of different common points in the intersectional orbital planes of Mercury and the Earth where one might witness a transit of Mercury, one of which occurs in May, and the other in November. Due to the different relative positions of the planets to the sun and each other, transits of Mercury occurring in May tend to have a much larger relative size of Mercury to the sun in comparison to those occurring in November, with the May events showing Mercury to be 1/158th the size of the sun, and the November events showing Mercury to be 1/194th the size of the sun.
Have fun this month!
May is also set to show us a very large Mars, with the Red Planet coming the closest to us that it will in this year's orbit.
Relevant Headlines:
http://www.space.com/32780-mercury-transit-2016-nasa-video.html
http://science.nasa.gov/science-news/science-at-nasa/2016/2016-transit-mercury/
https://weather.com/science/space/news/mercury-transit-may-2016