I have one of the Tamiya sets. They work well but are a little tricky to use. The problem with the Tamiya sets for me is that they are almost paste like and difficult to apply.
From what I have learned, and I am no expert on weathering, but there is no one right or wrong answer. Personally, I like to use oil paints to make a wash. I have 4 colors, black, white, raw umber and burnt sienna. With my limited skills, I can get just about anything done that I need to with these colors. For example, on landing gears and wells, I use a wash of raw umber on the parts to show hydraulic oil leaks and oil/dirt accumulation along joints and details. It works really well. You can use a brown or black wash to highlight panel joints depending on how dirty you want your bird to look. You can get oil paints and terpenoid at your local art store fairly cheap and they will last you a lifetime.
Here is a picture of my F8 Crusader and the main gear wells. Weathered with oil washes. I don’t think you will able to get this effect with the Tamiya sets.
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For wear, I drybrush some sort of metal color over the area to get the effect of paint being worn down to bare metal.
I also use Tamiya Smoke for oil stains and streaks. It works really well for me.
For dust and actual dirt (armor and trucks) I do have a a set of powders that I bought to dust things like tires etc.
Just play around and see what you like to use.
Good luck and have fun!
John