My main problem with clothes shopping is that I find good individual pieces, and then don't end up with enough to wear them with. A related problem is that I have one wardrobe for in and out of work. So to prevent the same thing from happening this spring, I'm trying to come up with a set of guiding principles for building a work wardrobe starting this spring. Keeping in mind this is for me, not for everyone, here's what I'm working with so far:
Business casual is still business. Without a dress code other than "appropriate for the position", business casual gave way to casual in departments that aren't customer-facing like mine. Erring on the side of "business" to emphasize the difference between work wardrobe and weekend. Someone pointed out to me one day that I looked like I was dressed for a date. That day I looked good, but I forgot the business. Distressed finishes, fashionable running shoes, coarser weaves and knits and so on are fashionable but aren't necessarily business.
The rule of thumb of business casual is three pieces. Introducing a jacket, tie, or appropriate sweater avoids the "meeting bare minimums" look. Jackets, incidentally, are indoor wear; maybe take them off in your desk chair if the chair makes the jacket ride up or crumple, but the point of dressing for work is being dressed that way at work, not just on the way in and out.
Fit is important. The most stylish clothes around will look awful if they don't fit perfectly, and clothes that don't fit comfortably won't get worn. Now that I've lost a bit of weight I have to avoid going too tight. Very few people in the standard retail size spread (up to 38" waist) look better in pleats than with a flat front because pleats make the hips, stomach and butt look bigger, and more pleats makes them look bigger still.
Buy good, versatile pieces, not necessarily the outstanding and interesting ones. I have a habit of buying lots of attention-grabbing patterns, colors, and styles. Attention-grabbing clothes take attention away from the wearer, and you grow tired of them quickly. The same goes for quirky styling. I bought a wool car coat this winter from Le Chateau that had a built-in hoodie-style hood and zip front that you could remove. It seemed like a neat variation on the car coat but for the money I'd have preferred to have picked up a better-made one without the gimmick. The hood's been zipped out for a month or so now. (My exception to this is French cuffs. French cuffs are absolutely OK even though they are attention-grabbing.)
Compared to wool pants, chinos do not look good on anyone. Jeans can look good on people, but people rarely look better in jeans than in well-tailored wool pants.
On the other hand, jeans with a dress shirt and jacket is a good way to do an "art department" business casual, but you can't buy for it; you need to buy the dressy parts to stand up on their own merits, and then sometimes wear them with jeans. The same holds for mixing in casual layers with dressy layers; a hoodie under a sports jacket works well unless you buy a sport jacket and a hoodie to wear together.
Don't worry about dressing too old as long as you shop in fashionable stores, because you have to go out of your way to do it. Fashionable stores sell current fashions. Older people wearing current fashions that suit them look good. Dressing too far up needs attention, though. Some say not to outdress your manager, but that can backfire. If you find yourself wanting to outdress your manager, then you'll probably do so by being more stylish rather than only more formal, which will come across as a difference in taste, not an attempt at gaining stature. Be sure not to outdress the first level of management that does dress to their position, though.
Dressing for work can be low-maintenance and comfortable. If at the end of the day you can't wait to get the tie off and the collar undone and into a pair of running shoes, then the clothes you're buying don't fit. People survived for a century in suits because they bought clothes that fit. There is much to be said for shopping in stores with staff who know how garments can be altered, and which have their own tailor. There's also much to be said for knowing a good tailor for when you find that perfect something in a chain store. And the ironing and hanging-to-dry and so on that makes t-shirts and jeans so handy goes away when you take your shirts and wool pants and jackets and suits to the cleaners. (Doubly so if, like me, your office provides next-day cleaning.)
You'll need wardrobes, not just one. Your lifestyle outside of work will dictate how many different sorts of clothes you'll need to have, and there will be overlap as you build your wardrobe, but identify early what wardrobes you need to build and buy things to go primarily in one of them. For example, I need business-casual work clothes, a few things for trendy restaurants and nightclubs, and neat but comfortable casual for the weekends. It's one thing to have a dress shirt you can wear to a nightclub, but if you try to buy shirts that work well both at work and out at night, or pants that are nice enough for the office and comfortable enough for the weekend, you'll end up with clothes that aren't very good at either thing they're supposed to do.
That's what I've got so far. I'll update things as I think of them.