The controls are weird at first to a modern gamer but if you play these controls should become natural to you soon.
Here are the controls as described in the help screen of the game.
Movement:

• Arrows Move
  
• A = Jump
  
• Z = duck
  
• Shift = Run (I found that you already have runlock on if you have Caps lock off)
  
• Capslock = runlock
  
• Ctrl = Fire
  
• Space = Open Use Command (this is important remember this)
  
• U = MOUSE aiming
  
• I = toggle crosshairs
  
• 1-0 = weapons
  
• ScrLock = holster weapon
  
• Enter = use item
  
• n = nightvision
  
• m = medkit
  
• Tab = map mode
  
• - + = zoom in out
  
• F = follow map node

I left some out as I'm trying to figure out what key they are or I haven't used them while playing.
What I found is that you can use the NUMPAD for moving and looking. This made my gameplay experience so much better.
NUMPAD MOVEMENT

• 8 = forward
  
• 2 = backward
  
• 4 = turn left
  
• 6 = turn right
  
• 5 = center view
  
• 7 = look up
  
• 1 = look down

Now this may seem silly but here is where I put my fingers when playing this game. Red is left hand and Blue is Right. This seems the most comfortable to me.
CHANGING CONTROLS
I've read in the discussion that it is possible to change the controls. Here is one solution I took from a discussion.
From topic:Setting up WASD config? Solution by: >M@tEo$<
For key binding, either edit the CFG file or drag and drop setup.exe onto dosbox.exe

Now I have not tried this solution so I don't know if it works or not! Comment if you know if it works.

So some people get turned away from this game because it seems it doesn't have mouse aiming. It actually does. When you start a game normally if you move your mouse your character moves but if you press U a message saying "mouse aiming on" should appear at the top of the screen. Now when you move your mouse your character can look up down left right, in every direction you want. Now there is a problem I had, how do i move? Sure I could use the arrows but then when I need to jump or interact I have to move my hand (sound lazy right?) If you press the scroll wheel your character will move forward allowing you to put your left hand where it normally set. (Near ctrl, space and A)

Mouse Controls
Scroll wheel (Pressed) = Move
Move mouse = Aim/look
U = turn on/off mouse aiming
Left Click = Use weapon (shoot, throw, stab etc)

Steps to Get mouse aiming
1 Start Level/ Mission
2 Press U
3 Mouse Aiming should turn on with a message at the top of the screen!
4 Enjoy

(being worked on)
Charles, VC, ♥♥♥♥♥ what ever you call them they are your enemy and will stop at nothing to kill you. The first VC you see is the simple VC wearing black shirt and a green hat with a back pack. You'll be fighting them alot. The next is a VC (possible NVA) wearing all OD who has a MG that will drop your life if you don't kill him quick or get to cover. I've found them mostly in bunkers or trenches. The next type is a VC wearing a straw hat and green shirt. His straw hat is what you'll see the quickest because it is bright yellow. This guy is an opium induced suicide bomber! Usually killing you if he gets close enough or dropping your health big time. Next is "rocket man" who i've never got a good look at because I usually die by his rockets or kill him first. He seems to be immobile and sitting on some thing, maybe a cannon or AA gun. (I can't tell) His rockets are slow and you can usually dodge them if you see him but do be careful as the rockets take alot of health away.

Land Mines
Use the minedetector, and crouch through the minefield to see the mines.
You can use grenades to blow the mines up but its not very effective. The explosion(s) will blow up near by mines too!

(being worked on)
You may meet soldiers along the way who can help you! The two that I've met is the Medic and the Radio man. The medic will run up to you and heal you. The radio man... well I'm not sure what he does. When ever you see one of these guys go up to them and press space. At the top of the screen it should say following. If the medic is currently healing you and you press space he wil not follow you so you must wait. I don't think any of these soldiers actually shoot back because I have not seen them fight back.

(being worked on)
Doors:

Radios: Radios are scattered all throughout the game and usually let you bombard an area with an airstrike or artillery. Some times you need it some times you don't some times it gets you killed. :D

Knife: Rarely used due to stealth difficulties and relatively low damage output.
M-16 (Assault Rifle): Can kill anyone on foot very quickly. Has 20 round magazine, with a max of 180 rounds. Ammo Packs carry 20 rounds.
M-60 (Machine Gun): Can kill anyone on foot very quickly. Has 150 round magazine, with a max of 450 rounds. Ammo Packs carry 150 rounds.
Shotgun: Normally used in close range situations, has a slow pump. Has a max of 40 rounds, and 10 round ammo packs. Not recommended
Sniper Rifle: Used for killing enemies at long ranges, with a one hit KO. Has a max ammo of 20 rounds.
M79 (Grenade Launcher): Dangerous to use at close range, but is sometimes useful at long. But other weapons (M-16 or M-60) are more effective for the same job. Rarely used.
LAW: Most useful taking out tanks or artillery. Ineffective against everything else.
Claymore Mines:
Grenades: Has a strange throwing arch and a weird blast radius, but can be useful. Can carry up to 6 grenades.
Flamethrower: Fun to play with, but ineffective due to short range and back blast.

Note: Your most used weapons will most likely be the M-16 and the M-60. Note that in NAM, aiming is not like a normal shooter (on default settings). You aim in the general direction, then rounds might hit.

(being worked on)
Hint from lil_misfit
" Listen to the voices talking and the artillery noises. If someone yells INCOMING just run out of the way as explosions usually follow."

Gruntsandwich
"You can bleed out once you reach under 10 health. Bleed out can RANDOMLY happen."

If you wish to help build this guide, whether its with screen shots of enemy or actually writing sections of it just comment or add me and I'll let you help! :D