Alexa Skills themselves are quite helpful. However, even with an updated Skills section in the Alexa app and the ability to add skills using only your voice, discovering new and useful skills is a less than desirable experience. So much so that Amazon actually created a skill called Skill Finder which, you guessed it, helps you discover new skills. Launch it by saying, "Alexa, open Skill Finder" or "Alexa, tell Skill Finder to give me the skill of the day."
Like all AI devices that use National Language Processing or NLP, Alexa does not understand all voices easily. But she learns to understand her people over time. She does, however, require people to speak in simple terms, with appropriate pauses, and use specific word orders. There are many times when she will say "I'm sorry, I don't know the answer to that question." More than likely, she doesn't recognize a word order or misunderstood the question.
If you want to do some casual research for a future trip, you can get fare estimates using the Kayak skill. You can say, "Alexa, ask Kayak where I can go for $400" or "Alexa, ask Kayak how much it costs to fly from Los Angeles to Dublin." The skill will ask for additional information and eventually provide you with a series of options and price ranges.