Something like the vim command-t plugin (https://wincent.com/products/command-t/) can make filenavigation very fast. That, the already mentioned C-j, C-k, C-h, C-l bindings, nerdtree, and bufexplorer (http://www.vim.org/scripts/script.php?script_id=42) and you're set for speedy file navigation. Then when you're comfortable with that there are things like taglist.vim to take advantage of ctags to kick it up a notch further!