@sholehAll users can earn credits by autopay, referring people to join Public Mobile and participating in the Public Mobile Community.. they say up to $20 but realistically it is only $15 / month.
Signing up people by using your referral code is probably the lowest hanging fruit.
You can earn a $2 autopay reward by adding Visa debit or credit card, referrals, and particpating in the community forum.
Here is more info about rewards.
Easiest way for me was when PM had the $25/$25 referral credit. That was a game changer.
But moving family/friends over is currently the best way