[looks sceptically at hatwoman]
So you wear skirts, you shop in nice shops and you have a colour scheme going on - as far as I can see you're doing pretty well in the style stakes...
Things to consider might be
Fun shoes - if you don't wear heels give them a bash, if you do and they're boring get some cheap fun ones to try out (leopard print very hot right now and great with brown). Also patterned tights.
Accessories - skinny scarves, big pendants, long earrings, bag with a bit of sparkle?
Colour (NB this depends on your complexion which I can't guess at so use your judgement) - wear the brown basics with turquoise, teal, orange, red, or hot pink. Wear the pink basics with olive green, plum, tan or navy.
Sourcing - try buying cheap things (check the fit first) from eg H&M, Topshop, Primark and Dorothy Perkins rather than investment pieces - means you can update regularly and won't feel guilty about getting rid of them when you're bored of them. Also go to Zara if you have the chance as they are masters of putting basics together in a non-dull way - even looking at their displays is an inspiration.
Pattern - ah. Now, I'm a bad person to ask about this as I'm not a great pattern / logo / motif fan and generally wear plain tops and plain bottoms. However I always add (eg) a statement necklace, long earrings, a big bangle or a scarf - today I'm slobbing, and hence wearing plain brown combats and a white top but have a brown / white / tan striped scarf in my hair which is just enough to stop it looking dull.
Another way to approach it is via texture - cord, moleskin, velvet trous/skirts; silky tops, fluffy jumpers, tweed etc all add interest to plain coloured stuff without being overbearing.
Can I ask how old you are and if SAHM/WOHM?