As the author describes, one reason technical people don't dress well is because they never learned how. Another reason is that techies are unconventional and don't place a high priority on mainstream standards. That being said, I've been fashion hacking for half a year now and the results have been great. Here's some concrete advice based on my experience. Note that I'm 20; people who have been professionals for 15 years and have kids probably dress differently. I'm also average height and average weight, so you'll have to make adjustments if you are tall/short/whatever.

Tshirts. Fitted solid color shirt with jeans that fit and shoes that impress = coffee shop, homework at the library, class. Easy as pie, and if you get the fit right and are in decent shape you look good.

Casual collared shirts. For general wear get bright, solid color fitted ones. Bar, restaurant, class, whatever. It's a very flexible look because you can switch in/out jeans and slacks. Express's 1MX shirts are a solid choice (http://bit.ly/cXBvxS) and very popular for this type of role.

Collared shirts for your suit. Go to a tailor. Get measured. Go to a store that sells suites like Men's Warehouse. Get two white shirts, a powder blue shirt, and a light gray shirt and you are done. Don't complicate things with strips or harder colors if you are just starting. If you want to add personality to your shirt you can do it with a tie You're going for these kinds of looks: http://bit.ly/bwI7zG, http://bit.ly/16mDVK, and http://bit.ly/97P8ld.

Hoodies. Buy two solid color ones, one navy and one grey. No branding, no weird details, no nothing. Solid color only. You can't really improve your look with hoodies, but you can really mess it up by buying one that isn't a solid color. Example (from JCrew): http://bit.ly/bcG2uB.

Graphic Tees. These are hard. You have to be younger to pull off a graphic tee and even then the single to noise ratio in terms of nice/ugly graphic tees is really high. You're probably better off avoiding them

Polos. it's very tough to find ones that fit well. I've had decent success with the custom fit from Raulph Lauren (http://bit.ly/clGtz5). But please, don't buy a polo with a huge logo on the front. Examples: This one from Raulph Lauren (http://bit.ly/arvbbg) and this one from Express (http://bit.ly/9VX3oB) are both BAD choices. A big logo just doesn't look good, and it makes it seem like you are brand dropping.

Something for parties. Something that's a little different. Do not buy this until you are ready. Go with your graphic tee or a regular collared shirt until you are confident enough to pick something cool. Example (from Express): http://bit.ly/9AOupm.

Jeans. Don't get designer jeans. Don't get them torn. Don't get them baggy. Regular or slim fit only. Get them in colors ranging from dark blue to blue/gray. Do not get light blue. Do not get jeans that are too long. They should never, never touch the ground and they should cover 1/4 to 1/2 of your shoe laces when you are standing.

Casual Shoes. Women notice shoes. Seriously. It's really interesting how much they look at your shoes. You can have everything else right, but if your shoes are big blocky white gym shoes, you have failed. I say this as someone who bought big blocky white gym shoes from freshman year in high school to sophomore year in college. The good news is that you can crowd source style selection by looking at Zappos's most popular (http://bit.ly/bep8vN). Once you have the style selection, just make sure you get a decent color. I own a pair of these (http://www.zappos.com/multiview/126799/14074).

Boots. Get something that looks good but does what it is supposed to do (stand up to the elements). I've had a good experience with Red Wing. The company used to make the shoes for the US Army during WWI and WWII, so they make a quality, durable product. I own a pair of these (http://www.amazon.com/Red-Wing-Shoes-Gentleman-Traveler/dp/B...) and they are awesome (but really expensive :-/ ). I've used them constantly in the snow and hold up great, plus they look good too.

Coat. You should get a wool pea coat. You should stop wearing your Northface that is the side of a small tent. Example (from J Crew): http://bit.ly/cVNqg2. Peat coats are a proven style that have been around forever. A nice coat is a really expensive investment and you don't want to buy one that will look bad when your style changes as you get older.

Sunglasses. Authentic aviators that have frames that fit your face. Done. Like the pea coat, aviators have been around for a long time and there are only a few people who truly don't look good in them.

Also, a few general tips:

Fit is the key to everything. It doesn't matter how much you spend on clothing or how well you match your colors. You will not look good if your clothes don't fit. Period. Everything you get should be slim fitting. Odds are 10 to 1 that the jeans you are wearing right now are far too baggy. Loose clothing was one of my most difficult habits to break.

Do not accept anything less than exactly what you want. Settling for clothing is the worst thing you can do. The legs on the pants you just bought half an inch too long? Return them. The collar of the shirt a little too tight? Return it. There are billions of styles and billions of fits out there. Taking a shortcut to save some time is not the road to success. You have to keep searching until you find a fit and a brand that you really, really like.

Focus first on making choices that don't look bad. It's actually really difficult to develop this skill. Once you can consistently make choices that aren't bad, you can start being more risky and shoot for things that look good.

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Yesh, that turned out to be longer than expected. It was kind of a brain dump, so I apologize if there are parts that don't make sense.

EDIT: One more thing. The first rule of fight club is you don't talk about fight club. Wearing nice clothes is something you do, but it's not something you brag about. Your clothes and brands don't define you and they don't change who you are. The only things clothes do is get in the way (if they are bad) or complement what you already have (if they are good). It's like being rude or polite in a conversation; it doesn't change the content of the conversation, but things can be really ugly or really pleasant depending on the choices you make.