So I know you can get Vim autocompletion with Ctrl-X, Ctrl-O but I'm wondering if you could rework it so it works with just pressing Tab (more like Textmate's snippets), or even just how I could remap it to something a bit shorter (even if I can't get fancy tab completion), as I find Ctrl-X, Ctrl-O a bit awkward.
I realize this question has been already answered, but you might be interested in a plugin such as SuperTab, which provides auto-completion and uses more than one type of auto-completion depending on the context and what type of completion you have been using.
The latest version of VIM includes auto complete Go to insert mode at specified line Ctrl-i then Press Ctrl-n while in the insert mode.
来源：https://stackoverflow.com/questions/6558168/vim-auto-complete