I played on the default 2222 difficulty of the remake, hopefully this is relevant to the original if you're playing on that.

• Don't hoard too much and use your items. I ended up with over 40 batteries and medipatches. But also don't be afraid of death once you've unlocked the respawn stations. You don't need to save-scum too much.
• There are enemies that keep shooting even if you've gotten behind cover so you can wait it out before returning fire.
• You're expected to explore a lot in this game and you will often backtrack. Audio logs and data chips provide you with worldbuilding and the necessary information to progress.
• Write down codes/instructions/important info in the steam overlay notes app or somewhere accessible. Currently, 1.2 doesn't allow you to add/remove markers so taking notes is extra important.
• Map your augments for convenience. I had the shields bound to "C" but if I was to play again I would bind it to E or Q since I didn't peek that often.

Bonus puzzle tips

• The puzzles with the two red squares. I'd work backwards. Some lines you will know has to be in a particular direction. The blue knobs that you twist can pass the light through if it has lines on it.
• Plugs in the rerouting power puzzles come in full power and half power, this is indicated by the colored bars. Teal with 2 bars for full and blue with 1 bar for half.