The photo above was taken in one of the late Duke of Windsor's dressing rooms before the auction of his estate. He was a man whose clothing appetite had few constraints. Most of the rest of us have to make choices, and men who have to make choices should have a wardrobe plan to help them make the most of their limited resources.
A good plan begins with an annual clothing budget. Once you've determined spending level that's right for you, review your existing wardrobe and determine both your needs as well as any options that would add to your sartorial happiness. Calculate what you think you can spend per item without exceeding your budget - if you're budget constrained, and few of us are not, one way to arrive at amounts is to set aside about 80% of your funds for a pair of dress shoes and four suits, overcoats or jackets and trousers each year (if you consistently acquire clothing at that rate you will eventually have a respectable medium-sized wardrobe with roughly eight or nine pair of shoes and as many suits or jackets and trousers for each season). The amount available for each item determines whether you are thrifting, haunting the sale racks or getting fitted for bespoke clothing.
With budget in hand, review your wardrobe. For example, I am concentrating on summer suits this year as several of mine are coming due for replacement. Look at the patterns and colors in your closet, compare what you have to what you should have, and you'll soon know exactly what you should be looking for. If, like me, you're buying summer suits, you'll understand that you need to pass on that 13 ounce air force blue flannel suit in favor of something more seasonally appropriate. Your plan will also help you realize when you've over-weighted gray and need to add some blue or have too many solids but not enough stripes. In short, it's the difference between a balanced wardrobe that makes it easy for you to look good every day and a closet full of clothes.