How can I find surface data points?

Do surface scanning missions. They generate random outposts with a data point for you to scan, and even give you a waypoint to the place once you honk your discovery scanner.

Obviously, you're gonna need an SRV and a discovery scanner (or scan the nav beacon, but that's inefficient). Also, a lot of these missions will get you a fine/bounty for trespass and private point access, so, preferably, do it in a cheap ship.

Quince used to be a great system if you're farming lots of those missions, and will give you some empire rank too while you're at it, but how many missions spawn depends on the state of the factions, so YMMV. If you get there, and see nothing good, try again in a couple of days.