Hi, Leddy,
you may well find that the brushes you're using are too small. I know its counterintuitive, but below a certain size, using smaller brushes actually makes painting details more difficult.
The reason is that very small brushes rarely have fine points, and hold very little paint. From this point of view, slightly larger ones are easier to work with, holding rather more paint and (assuming you're using top-quality sable brushes, and if you're not, you should) forming a finer point. I rarely work with brushes finer than '0', and prefer not to use less than size 1.
I'm by no means the world's greatest figure painter, far from it, but even I can achieve results like this Airfix 1/32 British tank commander:
and Presier 1/87 airline stewardess
using nothing smaller than a size '0'.
One further point. You may well be finding that your paint is drying too quickly, if you're using acrylics. The way round this is to add a drop or two of flow enhancer to your mix.
Finally, I'm afraid that painting fine detail on figures is not easy. It does take a certain amount of practice.
Cheers,
Chris.
Cute and cuddly, boys, cute and cuddly!