In my .vimrc file, I have a key binding for commenting out that inserts double slashes (//) at the start of a line:
.vimrc
//
" the mappi
Btw... if your primary problem is about commenting... you should check out 'nerdcommenter' plugin, its the fastest way to comment/uncomment your code in java/c/c++/python/dos_batch_file/etc etc.