Victoria Beckham certainly knows a thing or two about fashion, and this week she revealed one of her top tips to fans on Instagram.The mum-of-four shared a Story with her 28.8 million social media followers in which she posed in front of a mirror wearing a beautiful navy maxi dress.MORE: Victoria Beckham's surprising shopping habits revealedVictoria, 46, could then be seen standing on her tiptoes as she emulated what her outfit would look like if she was wearing heels. WATCH: David Beckham films