Here I'll teach you what you need to own, and how to wear in order to look good.
I'll start with shoes. Every guy should own these 4 pairs of shoes: 1) A pair of comfortable exercise shoes. Typically, you only wear these when exercising. 2) A pair of casual sneakers, converse are a popular choice for this. Stick with a color like black, blue, grey, or red. You're looking for versitility here. 3) A pair of black dress boots. These are wonderful, and when coupled with the right outfit, will make you look good. 4) Brown dress shoes. I suggest a cap toe or a wing tip, either is fine. Also, socks. You should own a few pairs of white socks for exercise. Otherwise, wear black or brown socks (depending on the color of the rest of your ensemble).
On to pants. The right pair of pants is essential to pulling something off. When shopping for jeans, avoid baggy fits, they make you look sloppy. Likewise, avoid ultra tight jeans you might see on an urban cowboy or Jeff Foxworthy. If it tapers, its bad. You want something more in a bootcut, aka snug all the way down, with a slight flare at the end. Also avoid super light colored jeans, a dark blue with a soft wash on it always looks good. When looking for dress pants, you want a pair that sits well at your waist, not your hips. Also, it should fall just right. This means that the cuff of the leg should stop right where the sole starts on your shoes. It shouldn't bunch up around your shoe at all. Also, flat front pants look best, though single pleated pants look fine as well.
Belts: Simple, you should own a plain black leather belt and a plain brown leather belt. I also own a white leather belt, but I never wear it.
Shirts: Shirts can be tricky, because they're largely a matter of personal taste. You should own many button up dress shirts that fit you well, of many colors. Start your wardrobe off with oxford blue, white, and black though. Polos are a fine choice, because of how they often look good in almost any color. Rugby stripes are your friend. You should own several white t-shirts to use as undershirts, also they're good for working out in. A few pullover hooded shirts are nice too. I'm not talking about the ones with your favorite team on them though. Something that fits you well, maybe striped horizontally. For some reason, girls love thermal long sleeve henleys on guys, keep that in mind. Also own many different t-shirts in different colors, with different designs and graphics.
Sweaters and Jackets: In the colder months of the year, layering will help keep you warm, and make you look good. You should own a few of the nicest sweaters you can afford to buy. I personally prefer V-necks over crew necks because you can wear a dress shirt better underneath it. Most sweaters look best in black, green, brown, grey, or blue. Don't let that deter you from choosing a different color if you think you can make it work. Sweater vests are actually really cool, don't let the image of a retired man wearing one scare you, me might have made that look good in his day. Beware of patterns or stripes on your sweaters, usually the plainer the better. Every man should own a dark blazer/suit jacket or two. Black, blue, and grey are the colors you're looking for here. Also, a nice "military style" jacket can look very fashionable, as is evident by their rising popularity.
Outerwear: Most men probably own only one coat. I own 6. However, if I were more conservative, I could skim that down to 3. 1) A camel colored overcoat. 3/4s length. 2) A peacoat. Black, Grey, or Navy blue. 3) A tan trenchcoat. Burberry if you have the means, as they are very last word in trenchcoat. I actually don't own a camel colored overcoat, I own a charcoal grey herringbone one, but thats only because I dont wear much brown. Also, you could substitute a duffel coat with toggles for a peacoat, but I usually think those make you look like you're 6. It should go without saying that these should all fit you well. That means the cuff of the sleeve should break right at the beginning of your thumb when your arms are at your side. Also, it should come in a little at the waist. If you wear a lot of suits, its ok for your overcoat to be slightly larger than normal, to accomodate the suit jacket.
Suits: I could write an entire article on suits, but I'll just give you the main points here. If you're buying your first suit or two, theres nothing wrong with going traditional. A 2 or 3 button, notched lapel jacket is never a bad choice. Your colors here are black, brown, grey, navy, or maybe khaki. Muted stripes can look good, usually in a shade darker or lighter of the original color. The cuff should stop just short of your shirts cuff, showing a bit of it. If you're feeling daring, go for a three piece suit. The vest should fit you snugly, never loose. With vests and suit jackets, always leave the bottom button unbuttoned. Its up to your own discretion whether or not to button the top button. Never more than 3 buttons. Only wear a double-breasted if you're in shape, and it fits you very well. You want to look like Harrison Ford did at the end of the first Indiana Jones, not every business man from the early 90's.
Ties: You should of course own a black tie. Maybe several black ties. College stripes, solid colors, simple patterns, and muted plaids are good; palm trees, keyboards, vertical stripes, pretty much graphics or designs of any kind, and american flags are not. If you're wearing a loud shirt, wear an understated tie to help ground it. Likewise, if you want to put some personality into your traditional suits, wear an interesting tie... and maybe a pocket square.