I have one rooted and one unrooted Android right now. I only download from playstore, xda, xposed and fdroid. Sometime download from other websites too but only after verifying they're trustworthy. I keep unknown sources turned off, only turn on while installing and turning off immediately after installation finishes.
Agreed with everyone above. Afwall+, Adaway, Xprivacy(if you install xposed) are must. Let me add minminguard and Youtube adaway if you use youtube app.
Does anyone know an alternative for xprivacy for the devices that don't support xposed like Nougat? Even if it gets support eventually, xposed takes a long time to get support on newest android version.