The only thing I've learned about 1999 mode is its difficulty is really overstated. All those Ken Levine articles must have been talking about something completely different that was eventually removed from the game.
Definitely helps that I'm familiar with the mechanics, but its still not the challenge Levine said would be. You could play this mode on your first time and whilst you'd struggle, it's more than manageable.
Corven said:
Corven, your better off just hitting restart checkpoint when you die. Sure it takes longer, but the money you save is worth it, especially in the long run. Getting those crucial vigor upgrades early on will make the late game more manageable.
EDIT: Actually lets share all my wisdom, though admittedly its not that much.
General Tip: Use Vigors, often. You get less ammo in 1999 Mode, and your weapons get horribly underpowered by the end game. Embrace that and focus on using vigors like possession to draw away fire, and bombard the enemy with vigor combinations. Still use weapons, but don't get attached, switch them often to suit the situation.
1st Rule: Never purchase health upgrades, you're better off improving your shield. Additionally split your infusions between Shield and Salt upgrades.
2nd Rule: Don't bother upgrading weapons early on, your weapons do the job that they need to without upgrades. Focus on buffing your vigors, they do far more damage and have better utility. In particular, Possession for Less and the Devil's Kiss Aid are far more effective than a standard buff for a single weapon you won't always have access to. Wait until the Vox Populi weapons (Which are much more common in the late game) start popping up to upgrade.
3rd Rule: Make sure you reset for the Urgent Care trousers, arguably the best piece of gear in the game. Its a frequent drop in the secret area in the Order of the Raven house.
4th Rule: Snag the Winter Shield piece of gear. It makes you invincible for about 5 seconds after your jump from a Sky-Line. That means that whenever you see a Freight Hook or Skyline you can continuously jump back and forth whittling away at the enemy.
5th Rule: Continuously switch tears, if the enemy breaks whatever you summon in, switch between a tear will renew it.