Beat Mission One on Normal Diffulculty
MRI Vision - Beat Campaign Mission One
EM Hack - Beat VT Mission One
Polarity Shield - Beat VT Mission Three
Magnetic Field - Beat VT Mission Five

To unlock, just beat the appropriate Virtual Training level in Campaign mode. The VT level will be the one that 'features' the multiplayer map (VT1 is in the Funhouse, VT2 is in Atlantis, etc.).

Funhouse - Virtual Training 1
Atlantis - Virtual Training 2
Moonraker - Virtual Training 3
Goldengate - Virtual Training 4
Uplink - Virtual Training 5
Carver's Press - Virtual Training 6
Bore Tunnel - Beat Hard Campaign Mission 1
Bath House - Beat Hong Kong on Hard mode
Mining Pit - Get All the Rogue Bonuses on one Campaign File

You can choose to use this skin in Multiplayer. Your character will look like Goldeneye.

Goldeneye Skin - Beat Easy Campaign
OddJob Skin - Beat Hard Campaign Mission 1
Pussy Galore Skin - Beat Virtual Training 4 on Normal Difficulty

Beating Virtual Missions unlock various things.

Hack ability - Beat Virtual Mission One
Virtual Mission Two - Beat Virtual Mission One
Atlantis Stage - Beat Virtual Mission Two
Virtual Training 4 - Beat Virtual Training Three
Moonraker Stage - Beat Virtual Training Three
Polarity Shield - Beat Virtual Training Three
Golden Gate Stage - Beat Virtual Training Four
Virtual Training 6 - Beat Virtual Training 5
Uplink Stage - Beat Virtual Training 5
Carver's Press Stage - Beat Virtual Training 6

To unlock You Only Live Once Mode complete the Campaign Mode on Hard.