[vim] How to select all and copy in vim?

how to select all and copy in vim insert mode? and is there another way to do it in normal mode?

I have tried visual mode and gg and shift + gg to select all and then yank, however that doesn't transfer it to the clipboard to be able to paste it in another application like skype or chrome browser.

I am sure this is a common task, and there are a lot of varieties by smarter ppl than me out there, please feel free to share yours.

ggVG 

will select from beginning to end

In normal mode:

gg"+yG

In ex mode:

:%y+

@swpd's answer improved

I use , as a leader key and ,a shortcut does the trick

Add this line if you prefer ,a shortcut

map <Leader>a :%y+<CR> 

I use Ctrl y shortcut to copy

vmap <C-y> y:call system("xclip -i -selection clipboard", getreg("\""))<CR>:call system("xclip -i", getreg("\""))<CR>

And ,v to paste

nmap <Leader>v :call setreg("\"",system("xclip -o -selection clipboard"))<CR>p

Before using this you have to install xclip

$ sudo apt-get install xclip

Edit: When you use :%y+, it can be only pasted to Vim vim Ctrl+Insert shortcut. And

map <C-a> :%y+<Esc>

is not conflicting any settings in my Vimrc.