As the person who maintains the standard, I should probably start by apologizing for not trying to do more to make something like that available. I had hoped that the FAQ or the comments on the spec page would help with some of that but it's obviously not enough. In particular my answer to someone's question about building an airport is probably my own better writing on the topic.
For buildings in LEGO at almost any scale I can recommend the new "LEGO Architect" book from No Starch Press. It covers micro scale building, though not Micropolis specifically, and has some really good techniques for replicating the details that can make a building look great.
If you want opinions on specific topics or ideas from many of the current people building for Micropolis most of the main traffic for discussion is on Flickr in the Micropolis group.
Or you can start with two points.
The first point is to look at the scale guide right at the top of the spec:
Scale: 1 brick is 9 feet, 1 plate is 3 feet and one stud is 7.5 feet. These are for reference only. The blocks are smaller than the blocks in a real city. Scale your buildings accordingly.
Next measure some real life things to see how that works out. For example a lot of US houses have between 8 and 10 feet between floors so if you've got a house with a flat roof then including protruding foundation and internal spaces it's likely to be about 24ft high, or (24ft divided by 3) 8 plates high. This ends up showing up in a lot of Micropolis modules as a brick (3 plates high) and 1 plate per floor. Expanding on that, a 10 story office building should probably be at least 13 bricks and 1 plate high.
The second point is to be flexible. Since most LEGO parts aren't very adjustable you can start to run into issues with items that are a bit smaller or a bit larger in real life but can be roughly translated into the scale. A great example of that is the standard Micropolis car, which is a single jumper plate with a 1x1 tile on top. However if a stud is 7.5ft on each side, then that jumper plate makes every car a 15ft 1970's land yacht. Most modern cars aren't much longer than 10ft which is actually closer to a single stud than two studs but a 1x1 plate with a 1x1 tile on top doesn't look like much more than a box.
Another example is the Micropolis city blocks themselves. Ignoring that in most US cities blocks are actually rectangular, at 32 studs our blocks are only 240ft long compared to the 260ft average of the short side of US city blocks. The long sides average 900ft. We experimented with that a bit when we were working on the original spec and there were several problems but the big ones included having too many different kinds of sub-block modules to make it work easily for a large layout and that while it was more "real" it just didn't look right to just about anyone. So we went back to the original idea for 4 16x16 quarter blocks to make one city block.
A good rule of thumb I've recommended to other people is to have a couple of those jumper and tile cars and put them next to whatever you're building and see how it looks. If the car looks too big then the building should probably be bigger. If the car looks too small, maybe take the building down a bit. You can make a lot of use of the various imagery options on the various mapping systems, both overhead and streetview, to give you an idea of what a car next to a building should look like in real life.
With both of those points in mind then the big takeaway is to try to both approximate scale but in the end be flexible about your implementation to fit the constraints of the medium and in the end build what you like and as long as it's got the roads, sidewalks, technic holes, and base height right it's a Micropolis module whatever anyone else tells you.