I don't really have rules in the dictionary definition; I let my aesthetic sensibilities define what I wear. Some of my common choices would be..
Minimalism: As an artist I love minimalism (hit
http://creativiity.the-enigne.org for some of my artwork). I try to keep my outfits to as few pieces as possible - Solids and lines (pinstriping or stripes) can supplement the definition of my body very well without detracting from it, so I love wearing pinstripes (diagonal and vertical in shirts).
Contrast: Black and white, dark and light. I don't always go this route, but I love contrast.
Rich saturation in colors - When I buy jeans with a "dirty" look, I usually go for the styles that have an almost unrealistic color. I love deep reds and blues in shirts. I can get away with green on occasion, but not all the time.
Snug fits: I like low rise hugging pants that have a boot cut or flare leg, and I want my shirts to supplement my body type, rather than just give me a rectangular look. Women are truely blessed in that they are created with absolutely glorious curves.
Some general things that I do would be..
I don't wear stuff with a fancy brand logo plastered all over.. I'm not rich, and I don't want people to think that I am - I just want to be well dressed.
I try to buy stuff that can work in multiple situations. I sometimes violate this (pleather pants is a good example, or the pink bondage pants I'm going to buy here soon

), but only on rare occasions.
No shorts - I do NOT have the legs for shorts... Plus, I don't own any good tennis shoes

I'm boots or flip-flops all the way

I don't buy anything that won't work with my new rock boots.
No polo shirts except for when required for a jazz/concert band performance (college) or work.

I'm not a polo shirt guy.
Cheap is a fashion - black t-shirts with pockets on the front are great (I don't wear em' all the time, maybe once every week or two), so are plain white t-shirts.