well in the orginal there's skills and augs. how you spend the skill points to upgrade levels is up to you and your style of game play, I start with computer skills (hacking), lock pick, and rifle.
first aug choice you'll find in the game is run silent vs run faster, I find run faster is more useful (i'm not much for sneaking).
well i hope i don't spoil the game, I practically played the game to death and remember the first half exceptionally well.
the first level can be completed without killing anyone- after meeting Paul Denton select whatever weapon you like the most. don't bother with the gep gun, it just wastes inventory space. unless you plan a frontal assault you don't need it anyway.
this is an approximate enemy layout of hte first "level"
http://i.imgur.com/CMXXN.jpgnot shown are the enemies in the liberty statue base. there's quite a few of them but if you go in from the back way ou can avoid most of them.
I recommend getting the tranq darts from paul, this way you can perform silent take downs and avoid gunfights. you don't start with much ammo (6 rounds).
you can also use the bots to kill the enemy for you. all you got to do is have them see you and give chase, and you run back to where the allied bot is. once the bot gets hit it'll mow down the enemy for you. then loot the body for ammo.
this is probably the best way to kill the first 3 nearest the south dock.
then just use the tranq darts at maximum range, shoot and run, the enemy will faint in a few seconds and you just double back and loot his body for more ammo.
you cna sneak in from the backside, on the way to the north dock. there's a huge pile of crates that when you climb on, you gain access to the upper decks of the liberty base. take out a few guys, use the outside stairs to the upper deck, the entrances to the statue (where the objective is) there have gas grenades, just frob them and they'd be deactivated, frob again and you get them in inventory. there's two dudes inside, kill them both, and go up the stairs, two more dudes, kill them, up a ladder and you'll get to the objective.
after you talk to the leader there's a aug canister near him that you can take, you can kill the first unatco troop you see for his sub gun but not any others (they're invincible).
then just head down to the unatco entrance (also labeled on map) for the next level.
there's way more to the level than this, you can explore later if you want.