Looks pretty nice. I would start by getting that seat closer to level -- but seat config is a very personal preference. Before that even, red blinky light for the rear.
This one is (like most) pretty cheap, plenty effective and (unlike most) comes with not just a seatpost clamp, but also a bracket for attaching to the back of your rack if it has a tab sticking down. Then, depending on whether you EVER ride in the dark, you'll be wanting a headlight. Opinions in that department are even more personal and contentious, but my personal (and not very contentious) recommendation is
this reg'lr flashlight, attached with two interlocking hose clamps. It's as bright as the sun, and with the adjustable 'focus', I find I can get a really good beam pattern from it. 12 minutes left on the auction, if you hurry you might get that one! Or another just like it for $25 or better. At that price, expect the batteries to be crap, and spend $10-15 from a better pair of 18650s (from an American company), and you'll be set.