You love a certain musical. Or want to know more about a show. One of the best ways to relive that experience (or prepare for it) is to buy the album. But which album? Be careful in your choice, because there are many different recordings of popular shows, and not all of those are created equal.
Think about the root of your interest. Did you just see a Broadway version of the show. Or was it a community theater production, or a high school rendition? Which songs do you love the most, and which actors sing those tunes. Those are the kinds of details you will need to think about before buying.
Start searching the Internet for all available options. Check Amazon.com but also Google and other search engines. Compile a list of what's available, then examine the important distinctions among the recordings.
Where was the recording made? London versions usually include British accents. American renditions don't. But a show set in Europe, "Cabaret" for example, might be better with the authentic accents. Then again, it depends on the singer. Maybe you really were hooked by the movie versions, Liza Minelli as Sally Bowles for example, or Catherine Zeta-Jones as Velma Kelly in "Chicago." Don't immediately reject the idea that unknown stage singers might be better, though, because they often are, and the original Broadway recording of a show many times is the best you can find.
Once you understand what is different about each album, try to preview as much as you can before you buy. Many record stores allow such sampling, particularly those that deal in used CDs. Listen to the renditions of each song in contrast with each other, so you can hear how each album handles each piece.
Once you decide what you want, buy it. And share your love for it with other people. The arts need as many advocates as they can generate. Talk about your new album, and tell people what you love about the show. Make them fans, too. Combat contemporary society's obsession with intellectual pabulum by spreading good work by the talented artists of this era.