I usually just lean on the local auto-tagging and OCR of the photo app, but sometimes if I take a pic that I suspect I’ll reference a lot, or just want it to be easy to find quickly even if I’m high or concussed or whatever, I’ll add a handful of likely keywords as custom tags.

My recommendation, however, is to favor delayed organization. While you may spend more time later digging to find the thing, it’s a good bet that (1) most things won’t need to be found i.e. most front-loaded effort would be wasted, (2) everything can actually still be found even if it occasionally takes a little longer, and (3) on-device image recognition and automatic cataloging tends to improve over time making everything more searchable retroactively.