Looking good, pretty tidy, the storm bolter looks great.
I would suggest getting another model and experimenting with thin washes, highlighting and dry-brushing. They're pretty good techniques for showing up model details and adding real depth to a paint scheme.
Also perhaps try thinning out the paint a little more on the base colour.
All in all though, much better than many of my early painting attempts.
Experimentation, practice and a steady hand are really key to getting good at painting.

Good to see the terminators coming along, and thats not bad highlighting for a first go I have to say!
Basing them up will make them a real difference too

How do people recommend painting white over a black undercoat? Paint it grey first?
Don't tbh. If you want a white finish then a white undercoat is really your only option.
Painting light colours such as white and yellow on black means you have a to build up a large number of very thin layers. I do this for some Brettonians I am painting for a friend but mainly because he had pre undercoated and I did not want to do it again or strip them down.
All mine above are painted over white undercoat.
something like the end of the gun and one of the middle panels might look good 

STOP JUSTIFYING IT PEOPLE !!!!! ��

