Requires scout (or higher) and to deliver 1 meta alloy to her. Scout is fairly easy to get (do a few sightseeing missions or some exploration and you will have it in no time). Meta alloy is sold at [Darnielle’s Progress in Maia](https://eddb.io/station/47951). Trip is fairly long, but easy if you have a decent jump ship (diamondback is good and cheap for this), you will need a fuel scoop to do this trip. There is a black hole in Maia that, when scanned with a DSS, should be worth about 50k, which alone will get you most of the way to Scout rank. It + the gas giants and the metal planet in the system (you should be able to see them all in the system map if you honked with a advanced discovery scanner). While at Maia, you will want to go to the planetary station “Darnielle’s progress” on Maia A 2 A (first sun, second planet, first moon). At “Darnielle’s progress”, go to the commodity market and buy 1 meta alloy (cargo racks are sold at the station if you dont have any). Go to felicity’s base in Deciat, go to the engineer tab, and donate the meta alloy. Felicity is going to be the first engineer you go too throughout the entire game (and in some situations, the only engineer). She has G5 (grade 5) FSD upgrades (+50% FSD range), grade 3 Dirty drives (faster ships, Palin is the only better and he sucks to unlock and get too), and grade 1 OC powerplants (10% more power for 1 sulfur), as well as a few other things.
Deal with 5 black markets (sell to 5 black markets) and pay him 500k, get some illegal goods (imperial slaves are good and will make you a nice penny, or just take a trade mission and abandon it, will let you keep the cargo but it is marked as stolen) and hit up EDDB/stations for stations with a black market, go to 5 of them and sell one of your illegal goods. Go to the dweller, and pay your 500k. The Dweller has G5 distributor upgrades (only one with that) and mid grade laser upgrades. Both of which are nice for any combat ship
Tod “The Blaster”
Earn more than 15 bounty vouchers (if you have ever done bounty hunting, then you already have this), and give him 100k of bounty vouchers (go bounty hunting, but instead of turning them in the system you earned them in, take them to Tod). Tod gives G5 multicannons (OC multis are incredible), and G5 railguns (no great railgun blueprints TBH, though the feedback cascade special effect is pretty great), as well as midgrade blueprints for most ballistic weapons.
get an invite from Eurybia Blue Mafia (look up on EDDB/factions for where they are and do some missions for them/trade in stations controlled by them) and provide 200 landmines (check [EDDB/trade/commodities](https://eddb.io/trade/commodity) for landmines (include planetary as most are sold on planets) near EURYBIA that have a supply of at least 50, get a good trade ship, and do a trade loop till you have donated 200 to Liz). Mostly just G5 missiles here which are somewhat nice on some builds, but she also has G1 armor/HRP upgrades which is nice as the G5 armor engineer is tougher to unlock.
Travel 300 ly from your career start (already done if you unlocked Felicity), and provide 3 Soontill relics (rare good, see the wiki, buy them and bring them to Liz, nice and easy). Liz does FSDs (nothing special if you have Felicity), G3 shield gens (somewhat nice, but G5s are right around the corner), G2 engines (same as FSDs), and G1 SCBs (nearly useless)
Now you are done with all the initial engineers, mostly just basic offensive combat upgrades and exploration blueprints, but plenty of good stuff. Use them, get them all to G3 and ~1/2 way to G4, and you will get introduced to the next tier of engineers. The next engineers are the golden geese of engineering, lots of really great combat upgrades here, however unlocking them is much tougher.