Decoration is not supposed to be useful, by definition.
I think it's interesting to set a budget and start noticing things that you like. Kind of random stuff that gets your attention for no apparent reason, just because it resonates with you.
And then you can think about how to fit more of "these" with your budget.
Could be board games, posters, cards, whatever. It's whatever makes you feel like yourself. Then hoard them in. :D