This is just my way of doing things, it may not necessarily work for you.
I upgraded the Sniper Rifle and the Shotgun, focusing on Damage before anything else. I didn't upgrade the recoil or the fire speed of the Sniper Rifle until late in the game, and I didn't upgrade the Shotgun all the way.
Possession: Fully Upgraded.
Charge: 1 Upgrade - invulnerability/shield recharge
Devil's Kiss: 1 Upgrade - increased damage
I had also upgraded Return to Sender with the decreased Salt cost, but I rarely used it, so I should have upgraded Shock Jockey to include the cascade effect.
If you have the season pass with the 5 extra Infusions, I would say put two into Health and three into Salts. Keep upgrading Salts and Health, focusing more on Salts if you frequently tend to run out of juice in the middle of fights. Shield is the last thing
I upgraded, and only after my Health and Salts were maxed.
Gear is a bit trickier, as it depends on your play style a bit more. And it's more situational, since you can swap it out at a moment if the combat requires it.
I never upgraded a single vigor, I just never had enough cash. the most I ever had was a little over $3000 and I lost half of that fighting the ghosts. Instead, I bought damage increases for most of the weapons. I maxed out pistol and hand cannon. I upgraded
salts and shields fully before I started on health. The vigors I found most effective were Possession and Return To Sender. The best thing to do is take your time, use your environment- ESPECIALLY tear allies! Don't try to rush.
I upgraded, Salts and Shields all the way first and then health.
I found a lot of money, so I upgraded, the machine gun and repeater all the way, handgun, sniper and shotgun (damage only) (I think I only died 4 times all the way through) I generally kept the sniper rifle on me at all times, and swapped out the others
as and when ammo ran out.
Vigors, I upgraded Devils kiss all the way, Bronco for both, and Charge which was just invulnerability.
Clothing , tended on the situation at hand, as they were easy enough to switch around as needed.
Don't know if anyone's mentioned it but if you come across a vending machine (any type) and you're stacked up on salts, zap them with possession and they'll spit some money at you. Sometimes not much, sometimes plenty.
It's a gamble that every now and then pays off big.
Is there little point in my upgrading shield then ?
I upgraded my shield to 5 and my salts to max with health to 7, I found the shields to be extremly helpful on the ghost and the handymen, once it got low or depleted i used an upgraded charge attack to recharge it, worked like a charm
1999 Mode is fairly easy if you get these upgrades;
1.Fully Upgrade Charge
2.Fully Upgrade Possession
3.Upgrade Salts First (fully)
4.Upgrade Shields Next (full)
5.Health will be upgraded to 4 provided you don't have the season pass; if not and you do indeed have it it will be level 10 by the end of the game.
6.Hope for the best in getting this gear as it is a live saver-Winter Shield, Tunnel Vision, Spare the Rod, Vampires Embrace, Blood to Salt,Rising Blood Lust, Brittle Skinned, Burning Halo, and Urgent Care.
7. For normal combat/skyline combat use Winter Shield, Spare the Rod/ Rising Bloodlust, Tunnel Vision (just aim a lot in other words), and the boots Urgent Care. *Btw this may be a case of wrong labels on the gear; I am not on my character at the moment
to check which gear is in which slot*
8.*Spoilers* Use Charge, Brittle Skinned, Burning Halo, Vampires Embrace, and Blood to Salts to efficiently take out the siren in about 10 seconds even on 1999 mode.
9.Fully upgrade the Hand Cannon (Sniping Weapon)
10.Fully Upgrade the Shotgun (Dont get too close or I will blow your brains out weapon)
11.0. Use Bucking Bronco *Somewhat Spoilers* Only on Zealots and use the shotgun to kill them.
12. Be aware my playstyle as well a tactics are used for hanging back, sniping with the hand cannon, making enemies kill each other, and in hard battles jumping from the skylines to the ground rapidly and kiting using the skylines. Speed is the name of the
game when using the skylines as Winter Shield only gives you a few seconds to shoot a few shotguns rounds then leave without taking damage.
13. Open everything in the game that says locked; also loot everything in the game besides health and salts that you dont need if you are already full. Fully explore every area before moving on to find all silver eagles and lockpicks in the game that you
may need. If you run ut of lockpicks at any time before finding a locked whatever you ar doing something wrong and haven't looked hard enough in previous areas for lock picks (This bit of advice on lockpicks only pertains to you if you have the industrial
Those are my 13 rules to playing the game; hope it helps. BTW you can buy upgrades from all stores; just never go into dollar bill menu and buy something. It is the only way to sacrifice the scavenger hunt achievement. All other upgrades are fair game though
and if you use rule 13 then you should have no trouble getting ammo, health, and salts and therefore have no reason to go to a dollar bill.