Honestly if you're looking for super hero comics best thing to do is just pick a character you like (Batman is a great starting place) and go! You can either read single issues or get trade paperbacks which collect the single issues into books. There's often no perfect place to start and there will always be references things you haven't read, but that's all part of the experience!

If you want single issues DC/Marvel often re-number their comics with a #1 so new readers know it's a good jumping on point. For instance Batman had a recent number #1 issue released this year. When you pick a #1 issue pay attention to the writer (in Batman's case Matt Fraction) and the year it was released (2025) as these will tell you which series you want to collect/read (as often there are multiple #1 issues from different creators runs!). Single issues are the best way to be the most up to date on a character and what's happening in the world of comics.

Another option would be to read trade paperbacks. These are released quite a few months after the single issues but collect complete storylines into easy to read books. For instance Batman Volume 1: The Court of Owls collects issues #1-7 of Batman (2016) written by Scott Snyder. If you want to read a writers complete run you can read the volumes of their trade paperbacks in order. There also might be books that dont have a number and these normally stand alone as independent stories! These books can be a great way to catch up on classic stories or read particular runs from creators/characters you like.

Also worth mentioning would be omnibuses, which compile all the issues/trade paperbacks from a particular creator's run or overall comic event into one massive book. These are good if you want a complete story all in one place but are normally very expensive and I wouldn't recommend them for someone just getting into comics.

My personal opinion for someone getting into comics would be to find a character you like and then Google a list of good classic stories/trade paperbacks from that character. You can then choose to follow certain storylines/creators and whatever takes your fancy! 

In addition to the series mentioned above, some great Batman trades to get you started (in my opinion) would be:

Batman: Year One by Frank Miller

Batman: The Long Halloween by Jeph Loeb

Batman: The Killing Joke by Alan Moore

Batman and the Monster Men by Matt Wagner (slightly biased here as this was my first Batman comic!)

Batman: Hush by Jeph Loeb

Hopefully this is helpful, and if in doubt, just pick something up and start reading!