PlayStation 2 MGS3 Help

Hi, I am new to this forum but one of the reasons i sighned up is because i needed help with MGS3: subsistence which i rented. Well im pretty bad at it but its kinda fun. For one whenever i sneak up to a guard they turn around and relize im there so i cant chokehold them but end up having to slam the to the ground unconsious. Also, i cant pick up enemy weapons. im not sure if u can but just wonderin... btw im at that base near bolshaya with electric fences if any1 was wonderin~i think im trin to find eva or somethin.:sigh:
For one you can't pick up enemy weapons so don't try.Second, try pressing the directional buttons to move sneakily.Finally, There is a boss soon so stock up on tranq darts. knock out a boss gets you a new uniform.