1. Use a primer, when they push my damn beginners painter tutorial through it explains why. Shake well, short even bursts, several coats, not when its humid.
2. Take an old brush dip the tips of the bristles into the color you want to highlight. Wipe all the paint off and then using a paper towel drag the brush over it a few times to make sure you have no paint hiding then you basically do what you were doing on the paper towel on the model, dragging the tips of the bristels over the model, what you are trying to do is get the paint to stuck to the hard edges of the model.