Hello Brent,
Adding the eyes as the last step is definitely doing it the hard way! I learned early on to do them first, even before shading the face. There are several reasons for doing this:
1). By doing the eyes first, you can "cut" them down to the final shape by going over "sloppy" areas with your basic fleshtone. I find the eyelash to be the most difficult bit to get right. As you said, trying to get a perfect thin line with just the right curvature is difficult, sometimes impossible. So I only worry about the lower edge of the lash where it touches the eyeball and iris itself. If I screw it up and slop paint all over the figure's forehead, who cares! I can just go back over the sloppy area and cut the top edge of the eye lash in to achieve perfection. The truth is, I cannot do decent eyes WITHOUT going back and retouching them with flesh tone! Waiting until last is counter-productive.
2). As stated above, by doing the eyes BEFORE shading the face, I can go back and perfect them with the basic fleshtone without concern about obliterating my careful shading on the face. This saves you a lot of work and heartache in the long run.
3). There is also the psychological element. Personally, I like to know "who" I am painting before I start in to do any other painting. The eyes are the focal point of the figure. What if you spent hours and hours perfecting a figure and then discovered you just could not get the eyes right to save your life? Then you have wasted a lot of effort on a figure that will never be any good! The eyes have it! If your figure does not have good eyes, then you can always pitch it into the scrap box and the only time wasted was doing those hideous eyes!
There are a million ways to paint a figure. But it is always the best idea to use techniques which make the job easier. Techniques which complicate the process should be rejected. With eyes doing them first has always been the best, and by far the easiest, way to go for me......
By the way, I would avoid oil paint for eyelashes. The paint is too "sloppy" for this kind of precision. I use Humbrol flat black. It is good and dark and can be thinned to get razor sharpness without it going transluscent on you. If you prefer acrylics then use those.
Cheers!!
Mike