Hi Paul,
Adjust the aperture setting on your camera all the way open. If it is an automatic camera and you cannot do this, then use the preset for "Macro" or "Fine Detail" mode. If these don't work, then back up from your work, and zoom in with the cameras zoom feature. Also, try to use more light in your photographs. Hope this helps.
With regards to the weathering, you need to stay calm. I will agree that right now the color and contrast are very stark and unrealistic, but not to worry. You just need to be patient, get some practice, and blend the weathering into the models' finish.
BTW - I have a suggestion - if you want to try a new technique that you haven't mastered and don't want to sacrifice a new build, I would suggest an older tank you don't like anymore or buy and build a cheap tank you dont care about. Then use these as a test bed for your weathering.
With regards to the tank in the photos, if you used a different medium of paint, (like oils or enamels on an acrylic paint finish or vice versa) then just remove what you don't like. If the medium is the same, then slowly and carefully "cut back" the rust a little at a time with either very minute amounts of paint thinner or with the base colors used to paint the tank. You will also be surprised what a good coat of matte finish will do to blend the colors together. Usually for best results, try to build rust progressively, start with a bare metal color, then add some brown and then eventually a little red or orange for rust. Rust is easy to overdo, especially since most WW II tanks did not last years and years, many only lasted months or weeks before they were destroyed or abandoned or repainted.
When you are done, if it still looks bad to you then begin to slowly blend the rust into the base color by applying oil, acrylic or watercolor "filters" or "washes" These are just highly thinned paint (90%thinner-10%paint) to the tank. This will reduce the contrast slowly and subtly. You can also apply dust and mud to the areas you really don't like if all else fails.
Hope this all helps. Don't give up. Also remember, there are thousands of articles, photos, posts, forums, and other references here on Armorama and the internet to learn from, and books aplenty of weathering models. And if all else fails, just learn from this one, that is how you get better. The build itself and the paint job look pretty darn good.
Scott Gentry