I prefer to use the stick on eyes, either the flat or 3-D style. I use either silver, chartruese or the Mirage type which have a pinkish tinge to them. As Lee S said the eyes tend to stand out on bait fish and most of the ones I've encountered have the same range of color, though I've seen a few with gold in the iris. I used to use red eyes, at times, but I didn't seem to get as many hits on them, also it really didn't seem "natural" for minnows.
I tie very few traditional streamers, but if you consider bait fish tied with the artificial hair, the occasional Deceiver or Wooly Bugger, streamers, then I do quite a few.
For bait fish patterns, I prefer using the clear mono thread for the head as it lets the colors show through, with Wooly Buggers I usually use thread to match the Bugger's color. What I do with them all is after I've tied the head and applied the cement, in my case, I use thin Zap-a-Gap, I take a pair of unserrated pliers and squeeze the sides of the head flat. It makes it easier to put on the 3-D eyes, and flattens out the head profile a bit.
Not sure what type paint you're using but you might try one of those fabric paints that has glitter or sparkle in it to make the iris. Some dry translucent. I've seen them in pearl, metallic silver or gold, not to mention glow-in-the-dark. That would give you contrast on a white head.