For skywatchers in the northern hemisphere, 2021
Start your search on January 15th when the waffle-thin crescent of the new moon helps point you in the right direction. The moon will be a radiant tile with only 7.4% of its surface illuminated by sunlight. If you do not see Mercury low in the west that night, return on subsequent nights at sunset. Mercury will rise higher in the sky every night and become easier to spot as it does, but the trade-off is that it gets weaker as it climbs up into the sky.
The diagram shows the view to the southwest at 1700 GMT on January 15th. Mercury reaches its greatest extension from the sun, and then its highest height in the evening sky on the 23rd-24th. January, but catching it early in the revelation will allow you to track its movement night after night. From Sydney, Australia, the planet will almost be lost in the glare of the sun. The growing crescent, however, remains lovely.