You have to exercise some due diligence. That means first making sure you're downloading an app from the developer or Google Play, and not from a third-party source. Second, read the reviews of the app wherever you can find them. If the app is malware, someone will be talking about it online.
It's also wise to install anti-malware software specifically for Android. Again, check reviews.
Finally, just do a search on the name of the app along with the word "malware" to see what turns up.
Answer
You have to exercise some due diligence. That means first making sure you're downloading an app from the developer or Google Play, and not from a third-party source. Second, read the reviews of the app wherever you can find them. If the app is malware, someone will be talking about it online.
It's also wise to install anti-malware software specifically for Android. Again, check reviews.
Finally, just do a search on the name of the app along with the word "malware" to see what turns up.