I use vim for just about any text editing I do, so I often times use copy and paste. The problem is that vim by default will often times distort imported text via paste. The way to stop this is to use
:set paste
before pasting in your data. This will keep it from messing up.
Note that you will have to issue :set nopaste to recover auto-indentation. Alternative ways of pasting pre-formatted text are the clipboard registers (* and +), and :r!cat (you will have to end the pasted fragment with ^D).
It is also sometimes helpful to turn on a high contrast color scheme. This can be done with
:color blue
I've noticed that it does not work on all the versions of vim I use but it does on most.