Supersoldier is the hardest difficulty in the game, enemies will kill you fast and health regeneration is a bit slower.
It's safe to say that the horrible FPS in this game makes this difficulty very annoying some times.

Here are some general tips for Supersoldier:

Take cover and make every shot count as you will run out of ammo occasionally.
Stealth is gonna be your best friend here, make good use of it a lot.
Avoid combat as much as possible.
Use grenades against crowds of enemies as they're really effective.

OR

If you wish to save yourself some time, you can download my Saves....

Crysis 2 - Level 6 & 12 [Supersoldier]
Downloads/id=207300/crysis-2-leve...ldier.html


Crysis 2 - Level 19 - [Supersoldier] (Credits to Fizzishin)
Downloads/id=50995/crysis-2-all-s...-save.html