How did you choose your collection theme?

I'm having a hard time honing in on what my collection should focus on, any advice on honing in on a theme?

I'm debating between collecting every print of my fave pokemon and it's evo line

era specific (certain year to certain year)

Strictly a few cards I remember from my childhood (this is like 5 cards) and trying to get a psa 8 or 9 version.

Just so many options, I know there is no right way, but how did you do it??