Weathering on an X-wing can be done with just pastel chalk. The actual application of it is simple since you just rub it on. You just need small, stiff brushes and the chalk. Pastel chalk also comes in the form of pencils, so those are what to use for small blast marks. You can get the chalk in bars, powder or pencils.
For drawing stark, black, ultra-thin lines, I recommend the Pigma Micron 005 archiving pen. I like using that pen for sticking some black shadow all over the recessed areas of those kibble strips on the X-wing's top and that center/rear hyperthrust section. Then I usually drybrush aluminum over it.
You might be interested in drybrushing too. That is done with the paints & brushes you already have.