The Capital One skill allows you to check your credit card balance or make a payment when one is due. This is secure: The skill performs security checks and requires you sign in using your username and password. Then, when you open the skill, you must provide a four-digit code to confirm your identity. Just be wary of who is around when using the skill -- anyone who overhears you say your personal key can access your banking or credit card info just by asking Alexa.
This shouldn't scare you away, however. Alexa-enabled devices are great to have in your home and, with a little tweaking, can prove to be very good companions. I’ve hand-picked some of the most useful and unique Alexa skills from the thousands that are out there. Many of these skills will not be enabled by default, so you may need to follow the proper activation steps before using each one for the first time. 
Google Assistant doesn’t have flash briefings in the Alexa sense — instead, you’ll be publishing your audio content as a podcast. This is a little more technical than Alexa’s process. First, your briefing will need its own homepage. Second, you’ll need to edit the briefing’s RSS feed to include snippets of code that are required for Google Assistant to recognize it in its directory — check out all the requirements here. Google doesn’t require setting up an Assistant action. Once you’ve included the necessary code in your RSS feed, your podcast will show up automatically within search results.
In the Alexa app, this is achieved by selecting the main menu button (found in the upper left-hand corner of the screen) and choosing the Skills option. From here you can browse Alexa skills by category or other criteria such as those favored the most by its large user base. You can also search for skills by keyword or name through this same interface.
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.