Make believe - I wore a pair of blatantly Dolce e Gabbana bejewelled slingbacks to a wedding this week end with a "make believe' Dolce spotty dress that was actually from Marks and Spencer. Unless you are amongst fashion experts nobody will ever know and you will have created a very designer look for a fraction of the price (and without trying too hard).
Pair a high street dress with designer shoes - from time to time high street dresses are just as good as designer ones (especially in the summer when cotton is just cotton!). To give it a more expensive look, always pair it with designer shoes.
Wear an expensive coat over jeans and a sweater - A good quality coat (and I mean something like a cashmere maxi coat or a sleek tailored overcoat) will instantly make any outfit look expensive. I find that a Burberry trench could be worn over a pyjama and still make you look chic!
Wear a denim jacket over your pretty dress - this is a trick that I use all the time. Not only does it instantly make your dressy items more wearable in the day, but it also adds a cool and laid back effect to your outfit.
Invest in a pair of designer jeans - something recognisable, like my favourite MiH Marrakesh flare. You could be wearing a Topshop T-shirt with them (or a Madewell blouse in my case), and still look the part. (Okay so it also helps to wear a designer bag ;-) like my Chloe Drew...)
Throw a fun clutch over your all black look - weather it's designer or not (this is my Prada cookie monster) a fun clutch instantly lifts you head to toe ensemble and gives your look a bit of a 'lift'.
Combine designer bag with casual inexpensive shoes - No one will ever think you are wearing a pair of £19.99 Mango espadrilles when your bag is a little designer flashy, so don't be afraid to wear your Chanel or Chloe bag with your Mango lace up shoes this winter.
Finish off your look with a pair of designer sunglasses - Even when you are wearing basics like jeans and a jumper, a pair of designer sunglasses will make your outfit look more expensive.