keen observation is needed, and simple math (like 4*4=16 kind of simple). the eye generally knows when things are off, even if finding what's correct can be harder.
precision is a given - if you place single pixels, you are precise, if you do not, then you're not making pixel-art.
drawing quality and projection accuracy do require practice or technical knowledge, but this can be picked up through any of the numerous tutorials or, for those really interested in an academic sense, books on the subject.
but no, you don't need to be a draughtsman to make a decent building. looking at what you're doing, paying attention to others, feeling what is right and what isn't, these are the most key.
for instance, if you have a particular question about a piece of pixel art, such as how to space these windows, posting in the appropriately-labeled "Pixel Art" section of this board is the best way to begin!