Sufyan: Glad to see you may decide to keep trying to get through the game. You are going to meet many interesting characters and decide the fate of the world if you keep at it! To be fair, the Hong Kong segment is by far the most complex part of the game where about 80% of the accessible areas are completely optional, mostly to find WELL hidden items and talk to people to flesh out the lore. The claustrophobic streets and lack of easily identifiable landmarks is quite overwhelming. Over a decade later and about ten playthroughs I still get lost occasionally.

Once you leave Hong Kong you will get more involved with the many conspiracies and spend less time free-roaming in the streets, spend more time in more focused environments with clear objectives. Paris is quite open, though not nearly as daunting as Hong Kong.

Playing it stealhtily and more specifically as a pascifist makes the game a lot easier and it also means you generally have less use for augmentations. You will only need them in very specific situations. Dropping down from the billboard (nicely done finding it on possibly your first playthrough by the way!) benefits greatly from having a well upgraded Speed Augment because it decreases fall damage in addition to making you run and jump faster and higher.

I'd say the only generally useful augmentations are Regeneration (a quick way to heal) and Ballistic Protection (once upgraded you can become a powered bullet sponge). I also like increased lifting strength, which I believe you have already installed, because there are plenty of places where pushing or lifting heavy crates and furniture is useful.

The invisibility augmentations, one for organics and one for cameras and bots, are not as useful as they seem because there is almost always a way to avoid the enemy and their security systems. Again, being a pascifist is the easiest way to play the game. You don't need augmentations, you don't need weapons. If you never engage and never get caught by the enemy it doesn't even matter if you are playing on Easy or Realistic. Keep a melee weapon for breaking objects and a cattle prod for taking out enemies that are hard to get around. Unless you know the game like the back of your hand you will need a gun too. The stealth pistol is ok, though I prefer to use explosives in those rare instances the game almost forces you to fight.

With this game there are so many different solutions available for each problem that no one thing is ever essential. Don't have enough lockpicks? Find a hidden button or break a window. Need to swim and you don't have good a good swimming skill or aqualung augmentation? Just use a rebreather item. Just remember that this is an older game which means you need to be careful with how you handle your game saves. You can save yourself into a corner with no healing items or ammunition (or on to a high drop from a billboard). Modern games make us lazy with all those abstract checkpoints and by sneaking us some extra ammunition if we keep dying in the same place a few times.

boct1584: Speed Enhancement also raises your jump height, which correspondingly raises the damage threshold for falling.

Regeneration will eventually heal you to full health, so if you can fall any distance and make progress downward, do it. Or heal yourself with medkits unless you ditched all of them when you installed Regeneration.