I use vim-plug to manage my vim plugins.

Preparation:

if you don't have neovim, you need to go to install it. For example:

Install vim-gnome in Debian.

$ sudo pacman -S neovim
$ sudo pacman -S python-neovim (python support)
$ sudo pip install neovim (support UltiSnips and YouCompleteMe)
$ sudo pacman -S xclip (support clipboard)
// $ sudo pacman -S vim gvim

If you have used the neovim.

$ mv ~/.config/nvim ~/.config/nvim_old

Install with:

$ git clone https://github.com/GuidoPaul/Vim.git ~/.config/nvim
$ curl -fLo ~/.local/share/nvim/site/autoload/plug.vim --create-dirs https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim
// $ git clone https://github.com/VundleVim/Vundle.vim.git ~/.vim/bundle/Vundle.vim
// $ ln -s ~/.vim/vimrc ~/.vimrc

Install plugins:

Launch nvim and run :PlugInstall

About plugins:

1. ack.vim

$ sudo pacman -S ack

2. tagbar

$ sudo pacman -S ctags

3. vim-instant-markdown

$ sudo pacman -S xdg-utils nodejs npm

NPM behind a proxy then install instant-markdown-d

$ sudo npm config set proxy=http://127.0.0.1:10801
$ sudo npm -g install instant-markdown-d

4. jedi-vim

$ pip install jedi

5. YouCompleteMe

you must read YouCompleteMe carefully.

C-family support

Install clang libclang1 libclang-dev in Debian

$ sudo pacman -S clang cmake
$ cd ~/.vim/bundle/YouCompleteMe
$ ./install.py --clang-completer --system-libclang

Go support

$ sudo pacman -S go
$ cd ~/.vim/bundle/YouCompleteMe
$ ./install.py --gocode-completer

JavaScript support

$ sudo pacman -S nodejs npm
$ cd ~/.vim/bundle/YouCompleteMe
$ ./install.py --tern-completer

In a word

$ ./install.py --clang-completer --system-libclang --gocode-completer --tern-completer

5. javacomplete

You can refer to this link for more information : javacomplete