Here's what I recommend

--Scan wakes. Like religiously. It's easy, and they are right outside the station. For me a no-brainer. Use what you get here to trade at a mat trader to get what you need. Datamined Wake Exceptions for the win Alex! (Encrypted Materials)

-- Load up the SRV and go prospecting from time to time. Use what you gather to trade for what you need. (Raw Materials)

-- Investigate every HGE USS and scoop up what's there. Again, turn this in to what you need at a mat trader. I also really like Combat Aftermath and Encoded Emissions USSs. (Manufactured Materials)

--Scan all ships in combat, supercruise and normal flight for encrypted mats, and if you destroy a ship it will leave some manufactured mats behind that can be scooped up.

This is what I recommend for everyday sort of play. This is not targeted farming. When you need a certain type of thing you will only find them under specific conditions

For the USSs you don't scan them per se, you scoop or limpet the mats found floating in there. Encoded USS will have one scan item for encrypted mats like a personal data beacon, and a few manufactured mats to be scooped up. HGE is best because it's all grade 5 mats. These are useful in themselves, but especially useful to trade down for lesser grades. You will note that there is a bonus if you stay within the same category when trading mats.

Use this page to find material traders near you. After getting some mats, you can go trade them here for what you need, at a cost.

https://inara.cz/galaxy-nearest/25/9163/