This is from a series originally posted on my original blog: Seefahrer Thayer. While I don't recommend it, you can view the original posts here. Because the content had value and useful tips I've decided to repost them here, however, they've since been heavily edited and updated.
My advice is to ask two.
Or, as the gentleman on the train advised when I asked him about London, "ask a tourist". Locals will probably pretend not to know. He said often tourists have been to where you're looking for, or have a good idea of where to find it. I thought it was a good point. Already I feel very able to help a tourist navigate Belfast and Dublin. But I've made the mistake of asking a local... who pointed me in the wrong direction. To be safe I check with at least two locals if I have a good idea of which way to go, and three if I have no clue. Again, go with your gut. Last night I listened to a Korean guy who told me it was the wrong stop... it wasn't but I didn't get off. I KNEW it was the right stop. I ended up having to run several city blocks to make it on time for the next train.