Aliases in VIM

I usually have a problem with VIM commands ":w" and ":q". I type them very quickly and don't have time to release Shift key. As result I get error messages which inform me that commands ":W" and ":Q" don't exist.

That's why I decided to create an alias for them. They are created by the following command:
command <new_alias> <source_command>
For example, my ~/.vimrc looks like this:
set nobackup
command W w
command Q q
So I obtain correct result regardless state of Shift key.