Hi guys, I am having problems with merging meshes in blender 2.73b. I want to merge vertices on my hand to the ones on the wrist, but I keep getting the right hand vertices combined with the left hand ones, like they mirror each other. I attached a photo before and after merging. I tried setting the pivot point and 3D cursor differently but it doesn’t help. What is wrong? The objects are joined before merging.
It’s always best to supply a demo blend file for others to review.
When problem solving you should first get rid of all the crap that may get in the in the way of you actually seeing what you have. Disable all modifiers so you can concentrate on the base mesh.
Look for stray vertices / edges / faces inside the mesh.
Remove any double vertices, then enable the mirror modifier.
If you see anything change then look at your mesh where that change occurred. Then the same with the subsurf modifier.
I have attached the blend file now, thanks for the advice. I tried all the things you listed, and then began separating the objects. Now I am stuck on that 
It seems that, when I disable the modifiers, half of the body disappears as well as the opposite hand. I will try separating hands and the body and transferring one hand to the other side.
Attachments
character face.blend (595 KB)
You see the problem, the hand should be on the other side then you mirror the mesh.
You don’t work on the side that’s being mirrored
Yep, I figured it out 
It all came into place when I transferred the hand to the original side. Beginner’s mistake… Thanks guys for all the advice!
Yep, I figured it out It all came into place when I transferred the hand to the original side. Beginner’s mistake… Thanks guys for all the advice!