You can't paint what you can't see.
To paint with precision, you must be able to see what you are painting and be able to see your brushwork in enough detail to be able to figure out what you want to do and then do it. I used overhead incandescent lighting for my first seventy five models or so (go Skaven!) but was never able to get them above basic tabletop quality. "Good from afar, but far from good."
So how does $2 help? You go to the dollar store and buy yourself a compact fluorescent bulb and a pair of +3.5 reading glasses. A CF bulb in a goose neck lamp (or ever better, two CF bulbs in two goose neck lamps!) will give enough light close to the mini to actually see the thing, and CF bulbs have a much better lighting spectrum then incandescent bulbs without getting nearly as hot. Trying to use incandescent "daylight" bulbs in close quarters can get to be uncomfortably warm. Use of specialized lights like an Ott light give good results, but the advent of the CF bulb has put them in the "diminishing returns for the price" category. When painting small details or freehand try the +3.5 reading glasses. You'll have to experiment with how far to hold the mini from your face, but the amount of magnification this provides is quite adequate for detail work. Also, the fact that you are looking through two lenses maintain binocular vision, something that has prevented me from effectively using single magnifying glasses in the past. I just couldn't judge where the brush was in relation to the mini. All I was getting were up-close-and-personal mistakes!
I've been using bright lights for a while, and only recently got the reading glasses (which I wear right over my regular glasses when painting.) I did some touch ups on Vayl's body armor using the glasses, and was surprised of the detail I had missed previously. Not only was I able to see what I had missed along with the less than tidy areas, but I was able to see areas where the color consistency were sorely lacking. Now I should probably go over all that fiddly armor and highlight the wolf grey with skull white. That should improve the pop quite a bit.
So try it! It's only $2 ya cheapskate!