Take a long, hard and objective look at what you've got.
When better to have a fresh look at your wardrobe than the change of season?
Some ideas
Take everything out of your wardrobe/drawers, including shoes and accessories. If you have a separate summer and winter wardrobe, now's the time to reunite them.
Make two piles; clothes you really really don't like/want or fit anymore, and clothes you like/love or that have potential.
Spring clean.
With everything out of your wardrobe, now's a perfect time to clean the wardrobe (and drawers) itself. A good vacuum, dust and wipe down the walls with warm water and a few drops of lavender.
Time to reacquaint yourself with everything.
With the clothes you've decided to keep, group all garment types together; jackets, skirts, trousers, tops, etc. Separate what are obviously for warmer and cooler temperatures, though many of our clothes are trans-seasonal nowadays, especially jackets.
Have a big try-on session.
Have an open mind when you're doing this. Mix and match everything and see what combinations you can come up with. Don't second guess what something is going to look like, just try it on. Invite a friend, or a stylist, if you're not overly confident. Say you have two jackets, three pairs of trousers and six tops, try them all on in multiple combinations.
Think in terms of transforming a garment/outfit from casual to work through to evening simply by adding other garments or different accessories to change the look.
The purpose of this exercise is to get the maximum use out of what you have.
If some combinations aren't quite right, would they respond better to different accessories or a different top perhaps?
What's missing? Having completed this exercise with, hopefully, some new combinations to play with, do you need any new tops, cardigans or accessories to fill any gaps or to refresh the look of your outfits?
How to organise your wardrobe.
Here are some suggestions; it's a matter of what works best for you:
Group by garment type - jackets, trousers, tops, etc. You could even manage a sub-group of this by colour. )
Group by garment length - short length garments all grouped together like tops, jackets, etc and then longer garments like trousers, dresses and coats grouped. Modern wardrobe organisers/units have two rows of short garments, one above the other, for very efficient use of space.
Group as whole outfits - this certainly makes things easy for that early morning rush. Just don't lock yourself into always wearing those combinations.
Group by purpose, e.g. casual wear, work-wear, occasion.
Most clothing transitions really well from say casual to work wear so this way may be a bit redundant.
'Don't Want Anymore' Pile
Sell them through Trade Me or a pre-loved clothing store. If you're selling through an online auction, presentation is the key - how the garments appear in the photograph/s and the wording you use. If you've got well-known labels, be sure to tell people so you get a premium.
Give them to charity.
Your old work clothes, if in good condition, would be much appreciated at Dress for Success, a worldwide charity organisation helping women who don't have the means to prepare for job interviews and start a new job. It's a brilliant organisation doing great work.
Organise a clothes swap with friends.
Give them to friends/family.