– Trade in 50(yes) markets and give him 200 gold, I have him first here as he is annoying to unlock if you wait. Trade in 50 markets means you need to sell something to 50 different stations. Start making a habit of every time you dock, open the commodity market, buy something, and sell it right back. After you have gotten your 50 markets, the station orbiting his planet (and 6 other stations in his system) sell gold, just buy it and donate the gold to him.
Get outsider with the empire (super easy), and provide 50 Kamitra Cigars. To get “outsider”, do missions for empire affiliated factions until you get “100% none” empire rank and look for a naval ascension mission, do it, and you have outsider. The Cigars are rare good, so same plan as Elvira, this time you will need to make a few trips as the station does not allow you to have more than a few at once, if it will take you more than 3 trips due to the purchase limit, I recommend you get a friend to help you, if you do not have any in your cargo hold, 10 minutes after you purchase them you can purchase more, so your friend just needs to buy as many as they can (after presumably you did the same), dump them, and you collect them (collector limpets help), wait 10 minutes, then your friend buys more and dumps them again. Do this till you have 50.
Mine 500T and provide 10t of Painite, if you hate mining, this will be one of the worst engineers. I recommend you go to a pristine metallic ring (use EDDB/body to find one near you, also [this guide will help you alot with learning how to mine](https://www.reddit.com/r/EliteDangerous/comments/4wmgja/general_mining_guide_20/)) and mine until you unlock both requirements. Painite is somewhat rare so don’t feel disheartened if you don’t see it on your first 4-5 asteroids. Do note, planets often have multiple rings and the one closest to the planet is usually the metallic one, Painite is ONLY found in metallic rings (platinum and palladium are also only on metallic rings, if you’re not seeing any of them, you are NOT at a metallic ring). Selene does G5 armor and hull, these upgrades are fantastic for making hull tanking much more viable. (BTW, if you got your 500t of mining and didn’t get 10 painite, there are several player groups that sell painite [EIC](https://discord.gg/s3jhUsy) and [TLC](https://discord.gg/UtccPnB) are 2 I am familiar with, prices do vary.
Earn more than 50 combat bonds and provide 1m of combat bonds to him, this one can be tough as Combat Zones (found in systems in war/civil war) are very difficult alone in and the money you get is split if you’re in a wing. I recommend you get in a wing. Fight until you have 1m in bonds and go see him. BTW, don’t forget to pick a side, or you won’t actually get combat bonds while killing (right panel, functions tab, very top, you need to do it every time you enter into a combat zone). He does mines and torps, nothing special, but reverberating cascade special effect on torpedoes is great for ruining a shield tank’s day.
THIS ENGINEER IS NOT REQUIRED TO UNLOCK ANY FUTURE ENGINEERS, you can skip him if you don’t care about his upgrades. Unlock him by getting an invite from Party of Yoru (check EDDB/factions for where they are, do missions until you get the invite, same as Elvira) and provide 25 Xihe Companions (rare good, see Hera for best way to handle them, expect 2 trips, I believe the purchase limit is 15-24 (yes, I know)). Most useful upgrades is for Frag cannons, which are very good, but mostly used in late game PvP.
Get an invite from sirius and provide 25 modular terminals. So, Qwent is just a pile of traps. First, you actually need TWO invites, one to get into the Sirius system, and one for Sirius to let you meet Qwent, both of which are from the same faction but do require “Allied” to unlock. Best way to get to allied and get the Sirius permit is to do delivery runs between Sothis and Ceos, once you have that, go to Sirius to Patterson Enterprise station, do a mission for them (it helps remind the game that you are allied with Sirius), and board flip (relog into different game modes) until the permit for Qwent drops. As you’re doing all this, keep an eye out for modular terminals (the Sothis/Ceos runs are good for getting more if you don’t have 25). These are ONLY acquired from mission rewards. If you got both permits and you still have a woefully low supply of Modular Terminals (or lost them due to a failure of some sort), there are several player groups that sell them [EIC](https://discord.gg/s3jhUsy) and [TLC](https://discord.gg/UtccPnB) are 2 I am familiar with, prices do vary. Now for the icing on the cake, he gives no blueprints that can not be a acquired elsewhere (Hera has all of them at higher grades), his only use is a middle man to get to Palin and Palin’s sweet G5 dirty drives (though, he is closer to the rest of the engineers than Hera, so if you don’t need G4-5 overcharge powerplant, he is easier to get too once unlocked).
You now have a solid list of engineers and can engineer damn near anything. The next set give you a few end game blueprints and some optimization blueprints that are not particularly important, but can help. Some of these engineers can take a while to unlock.