If you are not installing apps from third party markets or websites (so you get apps from the Play Store) and you're even halfway practical about choosing between the majority of legitimate apps versus the few obvious fake apps, then most people are fine with that alone. As with any app store, it's important to read app permissions, reviews and to look at the rating and download count, as well as other apps by the same developer (mostly to make sure it's who you're expecting it to be). A little bit of caution and prudence goes a long ways. If that isn't enough, I'd recommend reading about AVG and Lookout, but I generally also advise that many default functions of anti-virus software are detrimental and/or fear mongering functions, so caution and prudence there as well. Good luck!