Those are nice but one thing i would suggest is to think about composition, for example the long exposure picture of the cars lights blurring on the road is nice but the huge patch of black and distant city kinda ruins it. Maybe if you'd gone down on the road and found an interesting way of showing the image it would of looked a lot nicer. Experiment with ways of making each area of the image appealing to the eyes and interesting.
You appear to be interested with long exposures so mess around with things that aren't so obvious, everyone does long exposures of car lights. Try something a little less obvious and find new ways of showing it
Also with long exposures, i find you lose a lot of image quality unless it's mounted on tripod. You can see various objects blurring in the backgrounds due to the camera moving as you held it for the long time periods
Anyways good luck, i'll look forward to seeing more from you :tup:
Edit: I just remembered that for some coursework i did a while back i experimented with long exposure and did a small series of pics primarily as portraiture but mixed in some long exposures of fire. One picture was of a model stood beside a fireplace with the flames moving in such a way that it appeared he had a huge schlong that was best described as a fire tentacle.
Hope that gives you some ideas.
(I am in no way responsible for thread starter setting his friends on fire and taking pictures ok)