Keeping that in mind, I try to make my details bold, use a lot of contrasting colors that will stand out against each other, and use highlight colors that are at least one shade removed from the basecoat.
I paint rank and file a regiment at a time. It takes a lot less time and the regiment will have a more uniform feel too it. Just because you're painting quickly, doesn't mean that you're painting poorly. Take your time and make sure that you cover everything completely. Avoid being sloppy as you paint and your miniatures should turn out fine.
Leaders and independent characters are painted individually or with a group of like figures. It's still easier to paint all the armour pieces on 5 to 6 figures at a time than individually. When all the common basecoats are done, then I take the time to paint the individual details.