Ghosts Mode

Weapons:

The XM shotgun and the m60 are the 2 best weapons for ghost mode hands down.

Tactics:

Camp, find a nice high safe spot where you can see everything around you. You will want to be in a corner so no-one can sneak up behind you.
Rush, Just run out and shoot at anything that you think is moving. M60 is a great gun for this because of its large ammo capacity.
Group, Stick together with your teammates and pick off kills along the way
Spotter, Dont even look for ghosts, just go around spraying common spots and trying to find them
Base Camping: Camp at either one of the sites and wait....they have to plant sometime
Water Watching, it means what it says, just watch the water (if there is any) for any sign of footsteps

Tricks:

When shooting at ghosts try to anticipate their dodging movements. Also keep moving at all times. Never be a stationary target for the ghosts. Use narrow places and water to detect movement. Get earphones and use grenades to your advantage.

Always spray around and near the C4, many ghosts just stand there after its planted. SPRAY ALL CORNERS! this is the mistake most ghosts make, they hide in corners when the safest place is probably open area.

If you hear beeping of the C4 being set try and locate it and spray like crazy.
If you are getting overrun by ghosts my best advice would be to run straight back at them and spray like hell, this usually confuses them and breaks up there attack into more manageable numbers.