Get more putty, liquid type, (Mr Surfacer) on the kitbashes and let it dry a bit.

Then I go for adding some metal (photo-etch leftovers bought to a British guy at a local Model kit convention, I've got enough to play with for years), and scrib a little... I really don't like this kind of exercise, and the result is, to say the least, bad IMHO...

I add some plastic strips too (the one you use to hang up wires you know... I found this kind on the ground all the time...).