Not wanting to do any (more) damage here as I’m a complete body repair newbie so what would the experts do to fix this dent? Any tools I should look at?
tl;dr: It depends on what you’re trying to do. You can make it less bad fairly easily but a perfect fix is not a DIY job.
If you’d like a perfect fix, you should talk to a professional.
If you’re in a position like me, you might be looking for a solution that looks less bad rather than setting your hopes on a perfect fix. An older car might not seem like a place where you want to spend an amount of money that might be a significant percentage of its current resale value. There’s no reason to have to look at dents and blemishes that make you sad, though.
For a dent like that (assuming a target of less bad again), you’re actually in a decent position. That looks like a fist sized dent near the edge of the fender. If I was working on something like this (and I have), I would (and did ;-) assemble the following:
The plan is to push that indentation back a bit at a time, eyeball the result and repeat but stopping before you think you’ve finished the job. Stopping a hair early will reduce the chance that you’ll make a newly convex bump or crease. That’s just crazy making.
The steps are straightforward:
In short, less bad is totally achievable. If you’re trying to get back to perfect / new, you’ll need a professional’s help.
Either learn to ignore it, or get a professional to do it. If there is a bit of paint damage where the two panels join, you can touch that up to prevent a rust spot starting, but the paintwork on the panel itself looks undamaged, fortunately.
The reason this type of thing is not simple to fix is because when you made the dent, you stretched the metal sheet, so there is now a bigger area of metal than you need if you try to bend it back to the correct shape.
The only way to deal with that is to cut a hole in the dent to remove the "excess" area, and then beat the panel back into shape leaving a smaller hole than the one you cut out. Finally, you have to fill the hole and repaint the panel.
As you can imagine, doing that to make an invisible repair needs practice and experience, and you don't have either the experience or anything to practice on. It also explains why body repairs aren't cheap.
If you really want to repair this, the "best" option is likely to be a complete new panel, even though the damage only looks localized.