When taking a look from day to night, it's all about having three easy pieces on hand: a little leather jacket, a piece of statement jewellery, and a clutch. These items are relatively basic-most of you probably own them already-but they shouldn't be boring. Fit and material is key for the jacket; you definitely want one with thin leather (it's dressier) and a cropped silhouette. Theyskens' Theory makes a super chic option that's very simple and classic, but I also like the streamlined biker style from Helmut Lang. If you already have something in basic black, why not switch things up and get a cropped biker in white leather? Whatever you pick, just make sure it's very clean-this is not the time for trendy accents or details. As for your statement jewellery, don't be afraid of a glitzy necklace or chunky cuff. A bold piece of jewellery can make anything-from a white t-shirt to a chic sheath-look appropriate for evening. Last but not least, the bag! Instead of going for a simple solid-coloured clutch, add interest to your outfit with an embellished bag. Marni makes a couple of amazing options: one with bright yellow beading and the other in black and silver. If that seems too ornate, you can always just go for a pattern instead. Lanvin's diamond-print clutch is beyond gorgeous and sure to transform any office outfit into an amazing after-hours look!