Painting an army is a daunting thing. We all want those beautiful eavy metal armies that gleam in the dexes and white dwarves.
For the rest of us we just want to get paint on there, and avoid an army looking like its been dipped. It still requires time, but with a few lil tricks you can get them on the table. If your going to a 'con that requires painted minis then this might help.
I use the 3 colors approach. Basically pick the most dominant area, then the second most and finally a spot color. On my marines this was the power armor, the metalics and the eyes or flesh.
Then you want to wash those areas. Then the last important part is to paint the base, because as gamers we associate a finished base with a finished model. This combines with the 3 washed colors to fool the eye when viewed from a distance.
You can then go back at a later date and finish the models, but this method gets painted minis on the table pretty fast.