Bustier - Am currently obsessed with these. Though they're technically lingerie, I've seen a few people sporting them as plain old tops. I've gotten mine from Forever 21, Tobi, and Brandy Melville. You can even wear these under muscle tees with just hints of them peeking out.
Shorts - Distressed, acid wash, frayed. Spring and Summer are all about the high waisted shorts. They're perfect with bustiers since they are high waisted and will cover you up more.
Cardigan - Since it's probably too cold to just go out like this in spring, a cardigan is a must. Especially if you're like me and not daring enough to just wear the bustier by itself.
Studded Converses - Now, I am usually not a fan of sneakers but they are a definite must especially if you're constantly running errands. Plus, with summer coming up, it's the perfect time for a DIY!
PS1 - I've talked about this bag before (here), but I love this color for the springtime. So fun! And strap bags are my favorite because they let me go hands free!