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.

Go to The Bug Killer.

On HIP 16613 1, in the Pleiades Sector, you can find the remains of The Bug Killer, a crashed Anaconda with 2 surface data points that can be scanned for high grade data, and 3 cargo racks that can be shot for high grade raw materials. In order to find it, perform a surface scan of the planet, or take a heading of 270 until you spot a greenish glow on the surface, where the remains of The Bug Killer's SRV can also be found. The ship itself is only a few km from there.

Once you scan these two data points, and liberate the raw materials from the doomed ship, log out to main menu and log back in. This will respawn and reset everything. This process can be repeated until you fill up on the two data types that The Bug Killer provides.