City Lights

hey guys i haven't posted much lately but i got a camera for my birthday (Cannon EOS 600d) and i have been loving it i took some photos about 10 minutes ago and these were my favorites out of the lot. At the moment i'm using 30 seconds shutter speed 5.6 aperture and iso100. please tell me what i can work on photography people thanks.

shutter speed is too long, photos come out too bright

i would opt for a higher fstop rather than faster shutter
that way you will have more clarity in your photos as well