I know next to nothing of hiking, so I’d be interested in hearing of your trips and tips and whatever else!
My limited knowledge roughly amounts to go with someone (genuinely) experienced, have more water (and probably food) than you’ll think you need, good footwear, be wary of the mystery berry, and don’t try to pet/touch all the wildlife (no matter how cute they may seem).
I love hiking. I think you’ve got a decent start with what you’ve written already. I would advise getting familiar with navigating yourself with a map and compass, a lot of places don’t have phone signal so at a minimum download your map and make sure you’ve got the battery to last the trip and some extra. I definitely agree with your thoughts about carrying more water than you think you’ll need, generally water will be the heaviest thing will carry but one of the most important.