● See if official lineage OS (r/lineageOS) is available for your particular device. Flash it if there is. Then you can flash microg (see r/microg for more info). If you don't like much hassle you can flash pico version of Gapps (google apps) from the website (https://opengapps.org/)
● Use Firefox browser with uBlock Orogin, Decentraleyes, etc add-ons.
● Read r/privacy wiki to know more because it's an extensive list.