How to use only tab (not space) in vim

I prefer to use tab than white space(may be a little different from most of others)

But I found, when I hit Enter at the end of line, it will add some white spaces, but not tab. So, I have to delete them and press tab.

I want to know how to set vim as:

1. use only tab to indent the lines
2. a tab looks like 4-spaces, but actually is a tab
3. when hit enter at the end of a line, the new line is started with only tabs

I've googled for this for a while, but not found a good answer. Thank you in advance

UPDATE

The answer @Alok has provided works well in most of cases. But I just found, sometimes, it depends on the file type. For example, if you are editing a haml file, and there is a haml.vim in your vimfiles/indent/, then all the tabs will be converted to space. So if you want it to be tab only, you should modify(or delete) the corresponding indent file.

The settings you are looking for are:

set autoindent
set noexpandtab
set tabstop=4
set shiftwidth=4

As single line:

set autoindent noexpandtab tabstop=4 shiftwidth=4

autoindent can be replaced with smartindent or cindent, depending upon your tastes. Also look at filetype plugin indent on.

http://vim.wikia.com/wiki/Indenting_source_code

Late to the discussion, just for anyone who struggled to force the use of tabs. With the current version of vim (>8) it was required to set:

:set noet ci pi sts=0 sw=4 ts=4

which expands to:

:set noexpandtab
:set copyindent
:set preserveindent
:set softtabstop=0
:set shiftwidth=4
:set tabstop=4

We can also use this setup with only specific file types, taking advantage of setlocal:

autocmd FileType c,cpp,java,python setlocal noet ci pi sts=0 sw=4 ts=4

For furher reference, see: https://vim.fandom.com/wiki/Indent_with_tabs,_align_with_spaces