The building should be looking reasonable, but just a bit more effort will make it look a lot better, and this time we get to use a brush as well.
Firstly the stripes. I can't remember where I first saw this idea, but painting the raised vertical bands on some of the panels really helps by adding a bit of colour. The test building was yellow, for this one I chose blue. I try to go for different colours on the board, I think of it as individual owners adding a touch of personality to their otherwise quite drab and uniform buildings.
First mask off around the bits you want to paint. Masking tape is cheap enough; for this you don't need the really good stuff, save that for airbrushing. Just make sure it sticks down next to the area to be painted, but if its a bit loose towards the edge, that helps when you peel it off. If you're careful you can even re use it.
For this I used my Vallejo Game Colours, a dark blue than a lighter blue to catch the edges.
Finally I mixed some VMC Oily Steel with black and painted the bits I wanted to look metal (with a brush!). These were then highlighted with pure Oily Steel.
Other steps to consider; run very watered down black into the cracks to emphasise the shadows, Sponge (or drybrush) a sandy/dusty colour around the lower edges.
Add posters and/or graffiti.