One of the most common trappings of micronations I see is flags. There's nothing wrong with that - flags can help build a sense of identity for your micronation, and there are online groups devoted to micronational vexillology (the study of flags).
However, I also see a very common mistake when it comes to designing flags, particularly for new micronationalists. There's a real tendency toward making them too detailed, trying to fit everything in. Flags should be easy to describe and recognizable at a distance.
As an example, Slabovia's flag is fairly simple - three horizontal bars, the top and bottom being purple (to represent our royal heritage) and the middle being silver to represent cyberspace.
And, to me, this is a pretty good flag design. It meets the criteria I outlined above (easy to describe, easy to recognize at a distance). It's something we can be proud of.
Oh, yes, one more thing - try to avoid making your flag look like any other nation's flag, be it macro- or micronational.
