If you love casual street style outfits, why not pair a black v-neck t-shirt with jeans? And if you need to effortlessly step up your look with one piece, add a pair of black leather desert boots to the equation. Keep this getup in your front hall wardrobe come warmer days, and rest assured, you'll save a lot of time crafting a look on more than one occasion. This pairing proves that moving from your 20s to your 30s is no reason to shed casual style altogether.