What a good strategy for black ops zombies kino der toten?

Okay I have no strategy. I can only play solo and can only get to like level 6,,,, be as detailed as possible usually I just use my handgun and m14 until level 4 then i open the door on the top of the stairs on the right. then i get the submachine gun to take down the devil dogs,, then when i enough points,, if i make it that far,,, i open the door far to the right and get the mp40 and see how long i can last..... the farest I've gotten is level 8,,, I just wanna get to level 10 at least