id just ask advice from people you know who dress well and choose clothing you're comfortable in.
check this out:
The Sartorialist
it is quite "fashionable" but i think the people in the photos express themselves in their own way. Just basic things layered works well. Black, greys, browns, dark green, dark blue, white look good together.
going to a traditional tailor is good as a lot of clothing from mainstream stores are a terrible fit and look good once they are altered to your shape. i dont ever ask sales people for advice unless they are well dressed themselves. if you make en effort to pay attention to people's outfits on the street maybe you can pick out things you like about them and that would give you some guidance.