The Appraiser achievement is obtained by upvoting 25 landmark plaques. Upon completion, the player will be 25% of the way to the Master Appraiser achievement.
Master Appraiser Achievement
The Master version of this achievement is obtained by upvoting 100 landmarks.
Landmarks can easily be spotted by checking the map and looking for yellow name markers.
By default, players are limited to voting once every 12 hours, so diligence is required to make progress towards these achievements. However, the time between when you can vote will go down as the number of votes on your own landmarkss goes up.
The limits on how often you can vote make this one of the more difficult achievements to accomplish. The normal wait time is 12 hours between votes. This changes to six hours when you have received 500 votes on your own landmark plaques, and to three hours when you have received 1000 votes.
At one vote per 12 hours, the fastest you can complete this achievement is 50 days. At one vote per six hours, it's 25 days. The absolute fastest this achievement can be accomplished is in 12 and a half days, assuming you only start after you've received 1000 votes and you set an alarm to make sure to vote every three hours.