Creating a flag for your government is an important part of building a nation/government/house. But it can also be tricky, this is why I am writing some tips for creating a flag/emblem. The list below shows some things you want when making a flag.
-Keep it simple, but not too simple. This one is the most ignored, look at some of the flags on this wiki for example.
-Have at least two colors, ones that contrast well.
-Don't put text on the flag. It kind of just spoils the meaning. Having english text on a flag would make no sense if your nation speaks more than one language.
-Give it some meaning to the nation. This one is usually optional, but it helps build the lore of a nation.
-Your flag should also be able to show what kind of government your nation is. There are many examples of this in the real world and sci fi. Ex: the UN Flag.
And those are all the tips I have. Remember though that there are flags in Science fiction break some of these rules, and that is Okay! In the end, what really matters is how unique it is.