best thing for guys who don't have natural fashion sense is get it from somewhere. That means mags, catalogs, etc. The neat thing about catalogs is that, especially large store catalogs like Saks Fifth Avenue, will mix pieces from different designers to make one outfit, which is what most people end up doing anyway. In single-designer catalogs you're limited to outfits only made up of stuff from their line.
Pay attention to how different colors work with your complexion and hair color. For example, my cousin, who is gorgeous and brown-hair/brown-eyes darker skin and freaking six foot tall looks awesome in seersucker suit (a very VERY southern thing) whereas i, blonde hair bluegreen eyes, pale skin 5'8 do not.
Different designers will cut their patterns differently too. pay attention to whether something is "modern fit" or "city fit" or "slim fit" or any number of other terms. This will refer to how the shirt, you guessed it, FITS. For a guy like you with the sexy bod going on, you're going to want to try ALL of these on and see which one fits your body well. Don't be afraid to ask the salesgirl/guy. If you have broad shoulders make sure its not too tight. there shouldn't be tension on your delts trying to pull them together. Also "fitted" does not mean "tight" Usually you want fitted because while tight might look hot its a pain in the ass to move around in (expecially driving a stick shift, trust me)
A nice pair of straight, dark jeans (black or REALLY dark blue) from a good-fitting designer looks good with a button-down collared shirt and either a modern blazer (cheaply had from any number of dept. stores) or a leather hipster jacket.
This is just one look, more of a clean-cut casual look that still says "I'm fun" but also says "i'm mature and at least a little successful"
Oh, i'd love to actually give you an education in person. I love doing that. I have a few "students" here actually that i give lessons to.