If you can ignore most of the chattering comments, the basic menswear guides over at /r/malefashionadvice are a great place to start. If you are willing to spend some time learning, and spend a few hundred dollars on clothes, you are off to a great start. They have several different seasonally focused guides, but I think the Fall/Autumn one is the best place to start. I would also second your friend's advice, to buy things one at a time. Also, don't spend very much money on any one piece while you are still developing your personal sense of style. Stores like H&M and Gap are great for this stage.
I don't consider the basic MFA 'uniform' to be reflective of expensive tastes. I haven't been a regular there for a number of years, but the consistent contributors I'm familiar with are much more frugal-minded than the denizens of any other menswear forum I've visited. If you really do find their suggestions out of your budget, there's always the aptly-named /r/FrugalMaleFashion. The most expensive thing I've seen recommended there is a solid pair of leather boots.