It is a good start. Here are a couple of things that I do that usually gets positive comments.

1. On the tracks dry brush the keels, the area where the road wheels ride on the inside of the tracks, and the cross bars with a bit of flat aluminum
2. Use a number 2 or an HB soft lead pencil and rub it on all the corners and protrusions that might normally be rubbed by wear and tear.. usually on the edges of the fenders, around the periscope edges, cupola edges, you get the idea.
3. Run the same pencil around all the cracks between the hatches and openings in the hull. This is all pretty harmless since you can rub it all off if you don't like it. You can also use the pencil to imitate paint scratches.
4. Make a wash of a sand or mud color and slop it around behind the road wheels and on the tracks.

5. The lesson that finally got pounded into my head is that paint fades from the top down so if you are going to lighten paint pretend you are the light source (sun) and just lighten anything exposed from that source. if the light can't get to it, then the factory color should be darker unless worn off by use.

6. Tale your time and just have fun doing it.

7. More rust on the exhaust pipes.