One thing that often is poorly thought out in science fiction books is how trade works. I don’t mean the technology but how it work economically.

Trade of manufactured goods only happens when the cost of transporting something is cheaper then the cost of making it.

The thing is that with enough technology you can reach a point where you don’t need trade or it can’t be profitable enough to justify it.

You also have to take time lag into account. If you just got to a new system, and you find it has almost no uranium, which you need to power your nuclear reactors that does not mean you can send for it. If you have no FTL travel you would have to wait so long that the whole thing would be moot.

You can of course have trade be only possible because things are not natural. For example if only the home planet of an empire is allowed to mine and refine uranium then they could trade, even though it would not normally make economic sense.

Think about how trade works in your setting. Why certain places trade instead of making things themselves.