If you suddenly decided to change your style or you need to re-evaluate your look then the first place to make to make this change is your closet/wardrobe and cupboard drawers.
Decide what colours you are going to have as your main palette and which colours will be accent ones for some items and your accessories.
Separate your items into work, going out casual, going out formal and have a black bin liner to hand. Some things can be for holiday or the gym – worn items can be cut up for dusters and the rest must go!
This includes shoes, bags, scarves, costume jewellery the lot. This is something you need to do anyway come the end of the season and good quality item i.e. designer/unusual/ loved can be stored away in a storage box. I recommend these by John Lewis http://www.johnlewis.com/230364637/Product.aspx and you must insert a moth repellent such as this one by Lakeland http://www.lakeland.co.uk/product.aspx/solutions/bedroom!1779
Once your ship shape and have your remaining items, hang them in their category and try to hang them as outfits. Find one item that is your inspiration to build you new look around. I didn't expect to have a radical rethink but one item did contribute and inspire me towards my rethink because it a high street offering that is Marni-esque in its simplicity - a £15 Freedom necklace by Topshop of which I can't find a piccie of yet!