How to declare common parameter

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What is recommended ways to set common parameters in ROS?

In some of my nodes, I often want to use the same values for same purpose (e.g. subscribe/publish queue). Right now I'm setting parameters in .launch file. But since parameter comes with node name as prefix (e.g. /nodeNameA/paramNameB), parameters can't be generic enough (is it just because I don't know there's a way to nicely do this?).

Running a node that sets common parameters might be an option but right now I'm not planning to make such a thing, and more interested in better/ideal solutions if any. Thanks.