First of all, welcome to the community and thanks for registering here at Se7ensins.
There are numerous mods you can do, including infections. I for one say you should try using infections which can simply be found in the Modern warfare 2 lobbies section. You don't need anything for this, someone infects you in their game then you can use these infections online against opponents.
I say try World at war infections including No clip & God Mode. These make you invincible.
Hope you stay active here and enjoy your time. :thumbup: