belezabaub

I'm no fashion expert but... The importance of this sort of style is comfort. Think of it in terms of how Apple want to market themselves, cool but very useful at the same time. Don't wear two items that our the same colour, ie you can wear a light grey and a dark grey but don't get them too close in shade. Keep it loose but not baggy. Jeans should be dark, jean shaped cords are another option.
It should look nice but have a function, zipped hoodies are good because you can zip them up if your cold and put up you hood if it rains. Avoid anything dressy, like don't try to wear anthing but smart/casual trainers, no scarves neither.