Shorten the sleeves by about 0.5 inches and also shorten the trousers (they have a quite narrow leg opening, so they need less break) but don't touch anything else. The jacket has very clean lines and if you make it slimmer you will probably ruin it.
If this is bespoke/mtm, next time ask for a bit wider lapels, if you can. They aren't bad as is, but I think they would look better with more meat.
I also suggest wearing your pants a little higher in the back to get rid of the wrinkles in the back of your thighs.
I'd say don't wear it with black shoes.
Thank you for the detailed comments. Appreciate it. I'll have the sleeves shortened asap and talk to the tailor about shortening the pants (never really had anything shorter than these before).
The suit is MTM, and I sort of chose the thinner lapels as they seem to be more "trendy". Will go wider for my next suit.
And I didn't know that about the pants. I'll do that!