Look at all my ranks! I'm, like, so cool, guys.
Can you imagine if I were the one giving orders (lolz)? "Now drop and give me fifty...pairs of shoes" heeeyyoooo.
If you want to pull an army/navy/cadet look, it's important to stay consistent: choose your accessories wisely and don't go nuts on color. Your base color should be black or navy to compliment what rank you are: in this case I've got khaki ruling the world and it looks great with black.
As for accessories, keep them simple, and switch it up. I've got a Heisenberg on but you can wear a bowling hat, a baseball cap, a fedora, whatever flies your aircraft.
You can also go full boot camp and wear combat boots but I like these little Italian booties because they remind me of "one pair of Italian leather boots, one vinyl record album, Bert Bacharach plays his hits, one Swedish-made penis enlarger pump" because that movie is still great after almost 20 years.
shirt: c/o Ardene
boots: Giuseppe Zanotti (sold out) - find similar here
hat: Free People