If you have the lucky challenge to figure out how to make your clothes fit in a small closet, IKEA's PAX storage closet line, may be able to help. IKEA is a great organization source to purchase products to assist in solving some storage shortfalls in your home.
Though I have to caution, just like with a built in closet, really own and love everything in your closet so that getting dressed in the morning is an uplifting experience. I know closet organizing can be emotionally challenging especially if there are several wardrobes of different sizes in your closet.
So here are the basics to get started:
1st - Take everything out and only keep those clothes that make you feel good, fit well and are needed. This will require some trying on of clothes, if you aren't sure if something fits or not. Figure out what may need to be cleaned or fixed of the clothes that are the keepers. The remainder put in donate, if they are in good condition. Box up any clothes that don't fit, but you think realistically you will fit into within the next year.
2nd - Put clothes back in your closet logically - short sleeve / long sleeve grouped by color, skirts together, pants, etc. Put all the hangers in the same direction, and if possible have all of the same type of hanger (slim, fabric covered hangers are great and they save space). After an article of clothing is worn, turn the hanger the other way so that you have a visual of which clothes you wear and which you don't.
3rd - Group accessories and buy storage to accommodate them so that you can see what you have. Use clear shoe boxes, or put photos on shoe boxes if you like to box shoes, arrange by color or type if you like to store on shoe racks; scarves on a shelf or drawer; belts hung, etc.
If you have a closet that visually looks appealing and you like everything in your closet, it sets a positive tone for your day instead of possibly causing stress. Good luck making decisions for what to keep and what to let go as you switch winter clothes for lighter spring and summer outfits.