Truly, the quickest way that I know of is doing the Resistance "round 10" method but it is boring AF. You can google how to do it. I took quite a few newer players in there to show them the ropes on this and now I nearly despise that whole WSP/Resistance area. I would make a run or two though to help you out if needed.
People always balk at my response to this, but 3,500 hours across 2 accounts has led me to believe the easiest, while still being fun, way to gear up is doing the boss run loop in the LZ. They re-spawn every 4 hours PER CHARACTER. So, if you have multiple characters you can run it repeatedly. With a friend, you can actually run it indefinitely if you do it a certain way. Just about any build will work as the bosses are challenging level (yellow bar) and surrounded by regular red bar enemies.
If you are into PvPvE then by all means go to the DZ but then that prized item that finally drops for you is up for grabs for anyone that wants to gank you as you try to extract it.
RedBull eluded to the gear score but even though I know how it works, it seemed a little confusing to me (no offense Redbull). The regular yellow, gear sets, and orange gear will max out at an average of 286. Only classifieds in all 6 slots fully optimized will net you a 291 gear score. I'll note however that there are a piece or two that will show higher. It seems like it might be the gloves that are 293+. Weapons max out at 286 and keep in mind that score reflects all 3 weapons equipped including the sidearm. The optimization station is to the right of the crafting and recalibration tables in case you didn't know. It seems like there is one in the WSP/Camp Clinton but not 100% sure on it since I don't go there much anymore.
Another thing to note is you'll see veteran players running around with 283 or 284 scores and wonder why. Almost always they are skill players. Since dedicating all your stats to electronics, you won't have enough F/A and Stam to proc the weapons perk's. So, many run a 228 level gun in one of the 2 main slots. This way, one can proc the equipped skills since the weapon in hand determines which extra boosts you get.
https://edubirdie.com/correct-my-essay Most will run 3 of these 4: Destructive, Ferocious, Dedicated, and often either Sustained or Predatory (I prefer the latter). They then run a 286 level weapon in the other slot in case you need to finish off a shotgun rusher charging at you. For mine, I use Destructive, Ferocious, and Dedicated on my 228 level weapon and Predatory on the free slot on my 286 weapon. If I am low on health, I'll switch guns to proc the healing, then switch back. I also have an all electronics Alpha build that automatically gives you 4 slots as the sets perk. It is pretty good, but it doesn't have the skill haste of a Tac build. I love to experiment with skill builds. I've also got a few hybrid builds with the Ninja bag that can be quite unique feeling. It keeps the game fun for me.
He mentioned the Div Tech cost and ways to get it. Since I don't do the DZ anymore, I can't ever get the weekly so what I do is log in nightly with all 4 characters on each account and run the daily combat and daily crafting. This will take you from 10 minutes (for all characters) to probably at most 40 minutes. That will net 200 div tech per night; enough for 4 optimization "rolls". If I have more time and want to play more, I'll then do Daily Survival.
They have stated that the Global Events will be coming back but I have not yet seen a date. If/when they do, they are probably the absolute best ratio for time spent vs rewards gained. But, during a GE, you can only get the gear sets allotted for that specific event (in the caches, open world will still drop normal loot pool). There are generally 4 set items and they do repeat some, and it is on a cycle of the 6 events so it would come back around. I always suggest getting the plain GE caches first if you don't already have much classified gear. However, once you start getting stocked up on the items the event has to offer, then I'd suggest buying the more expensive $3k caches. They have one item and it is guaranteed to be classified. But, they also contain a random amount of Div Tech. I monitored it during one GE and I think I averaged 31 Div Tech per cache during the entire event.
As always, my replies turn into a novel. But, I like to help players that need it. While not new, if you need a hand or more info let me know. My gamer tags for my 2 accounts are Bambihunter1971 and Bambihunter71. I generally play the 2nd one as the 1971 account is 100% optimized across on all 4 characters and have done all the commendations I intended to. I do occasionally fire it up though.